Exhibit 4.21

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “1933 ACT”).  PURSUANT TO THE NOTE PURCHASE AGREEMENT, THIS NOTE HAS BEEN ACQUIRED FOR INVESTMENT ONLY AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF REGISTRATION OF THE RESALE THEREOF UNDER THE 1933 ACT OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY IN FORM, SCOPE AND SUBSTANCE TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.

ONSTREAM MEDIA CORPORATION

INFINITE CONFERENCING, INC.

ENTERTAINMENT DIGITAL NETWORK, INC.

AV ACQUISITION, INC.

ONSTREAM CONFERENCING CORPORATION

MEDIA ON DEMAND

HOTEL VIEW CORPORATION

OSM ACQUISITION INC.

AUCTION VIDEO JAPAN, INC.

SECOND AMENDED AND RESTATED SENIOR SUBORDINATED

SECURED CONVERTIBLE NOTE

FOR VALUE RECEIVED, Onstream Media Corporation, a Florida corporation, Infinite Conferencing, Inc., a Florida corporation, Entertainment Digital Network, Inc., a Florida corporation, AV Acquisition, Inc., a Florida corporation, Onstream Conferencing Corporation, a Florida corporation, Media On Demand, Inc., a Florida corporation, Hotel View Corporation, a Florida corporation, OSM Acquisition Inc., a Delaware corporation, and Auction Video Japan, Inc., a Tokyo-Japan corporation (collectively, the “Company”), as co-borrowers, hereby promise to pay to Sigma Opportunity Fund II, LLC, located at 800 Third Avenue, New York, NY 10022, or its registered permitted assigns (the “Holder”), or order, the principal sum of One Million Five Hundred Eighty-Three Thousand dollars ($1,583,000) or such lesser amount that is due hereunder, on the Maturity Date, and to pay interest on the unpaid principal balance hereof at the Applicable Rate from the date hereof until the same becomes due and payable, whether at maturity or upon acceleration or otherwise.  Any amount, including, without limitation, principal of or interest or fees on this Note, that is payable under this Note and that is not paid when due shall bear interest at the Default Rate from the due date thereof until the same is paid (“Default Interest”) and becomes a part of the principal.  In addition, in the event the Company fails to pay the entire outstanding amount owed under this Note on or before the Maturity Date, then the Maturity Date shall automatically extend for an additional six month period to April 15, 2016, provided that (i) no Event of Default is then occurring and (ii) the Company has entered into an amendment to the Rockridge Note to extend the maturity date to a date no earlier than April 16, 2016 and the Company has provided a copy of said amendment to the Holder.  Regular interest shall accrue and compound monthly on the principal amount outstanding and be payable on the last day of each month, in cash, with the first payment to be made on September 30, 2015.  Regular interest on this Note shall be computed on the basis of a 360-day year of twelve 30-day months and actual days elapsed.  This Note may be prepaid by the Company at any time. Upon the occurrence of a Repayment Event, the Company shall repay all outstanding principal and interest on the Note due as of the date of such Repayment Event, first toward interest, then fees and then toward principal; provided, however, that this Note need not be repaid in full upon the occurrence of a Repayment Event described in subsection (i) and/or (ii) of the definition of Repayment Event if the amount of such proceeds is less than is required to repay this Note in full, in which case such lesser amounts shall be paid.

1

All cash payments under this Note shall be made in lawful money of the United States of America and shall be made by wire transfer of immediately available funds to such account as the Holder may from time to time designate by written notice in accordance with the provisions of this Note.  Whenever any amount expressed to be due by the terms of this Note is due on any day which is not a Business Day, the same shall instead be due on the next succeeding day which is a Business Day.  Certain capitalized terms used in this Note are defined in Article III of this Note.

The obligations of the Company under this Note shall rank in right of payment and in all other respects senior to all current and future obligations of the Company for borrowed money or the purchase price of property other than the Senior Debt.  This Note is issued pursuant to the Note Purchase Agreement, dated September 21, 2015, and the Holder of this Note and this Note are subject to the terms and entitled to the benefits of the Note Purchase Agreement and the other Transaction Documents.  This Note is securitized against 100% of the assets of the Company and its Subsidiaries pursuant to the Security Agreement and subject to priority claims on such assets held by the holders of the Senior Debt as well as the terms of certain Intercreditor Agreements, as amended, entered into between the Company, the Holder and the holders of the Senior Debt.

The following terms shall apply to this Note:

ARTICLE I

CERTAIN COVENANTS

Until this Note is repaid or otherwise satisfied:

1.1       Limitations on Certain Indebtedness.  The Company will not itself, and will not permit any Subsidiary to, create, amend, assume, incur, suffer to exist or in any manner become liable in respect of, including, without limitation, by reason of any business combination transaction (all of which are referred to herein as “incurring”), any Indebtedness other than Permitted Indebtedness.

1.2       Payment of Obligations.  The Company will pay and discharge, and will cause each Subsidiary to pay and discharge, subject to the terms and conditions of the Note Purchase Agreement, all their respective material obligations and liabilities as they become due, and shall not accelerate in any material respect the payment of any such obligations or liabilities, except where the same may be contested in good faith by appropriate proceedings and the Company shall have established adequate reserves therefor on its books.

1.3      Maintenance of Property; Insurance.  (a) The Company will keep, and will cause each Subsidiary to keep, all property which, in the reasonable business judgment of the Company, is useful and necessary in its business in good working order and condition, ordinary wear and tear excepted.

(b)       The Company will maintain, and will cause each Subsidiary to maintain insurance in at least such amounts and against such risks as is reasonably adequate for the conduct of their respective businesses and the value of their respective properties.

1.4       Conduct of Business and Maintenance of Existence.   The Company will continue, and will cause each Subsidiary to continue, to engage in business of the same general type as now conducted by the Company, and will preserve, renew and keep in full force and effect, and will cause each Subsidiary to preserve, renew and keep in full force and effect, their respective corporate existence and their respective rights, privileges and franchises necessary or desirable in the normal conduct of business, except where the failure to do so would not have a material adverse effect on (i) the business, properties, operations, financial condition or results of operation of the Company and the Subsidiaries, taken as a whole, or (ii) the ability of the Company to pay and perform its obligations under the Transaction Documents.

2

1.5       Compliance with Laws.  The Company will comply, and will cause each Subsidiary to comply, with all applicable laws, ordinances, rules, regulations, decisions, orders and requirements of governmental authorities and courts (including, without limitation, environmental laws) except where compliance therewith is contested in good faith by appropriate proceedings or where the failure to so comply could not reasonably be expected to have a material adverse effect on the Company and its Subsidiaries taken as a whole.

1.6       Investment Company Act.  The Company will not be or become an open-end investment trust, unit investment trust or face-amount certificate company that is or is required to be registered under Section 8 of the Investment Company Act of 1940, as amended.

1.7       Limitations on Asset Sales, Liquidations, Etc.; Certain Matters.

Except when the Holder is paid due to a Repayment Event, the Company shall not:

(a)        sell, convey, lease, license or otherwise dispose of the assets of the Company or any Subsidiary other than in the ordinary course of business consistent with past practice or in compliance with the occurrence of a Repayment Event; or

(b)        liquidate, dissolve or otherwise wind up the affairs of the Company or any Subsidiary.

1.8       Limitation on Certain Issuances.  Beginning as of the date of this Note and so long as the Note is outstanding, the Company shall not, and shall cause each Subsidiary not to, without the prior written consent of Holder, issue or sell or agree to issue or sell any debt securities (other than Permitted Indebtedness).

1.9       Limitations on Liens.  The Company will not itself, and will not permit any Subsidiary to, create, assume or suffer to exist any mortgage, lien, pledge, security interest or other charge or encumbrance (including, without limitation, the lien or retained security title of a conditional vendor), all of which are referred to below as “liens”, upon all or any part of its property of any character, whether owned at the date hereof or thereafter acquired, except:

(a)        liens upon any property of any Subsidiary or Subsidiaries as security for indebtedness owing by such Subsidiary to the Company;

(b)        liens securing this Note;

(c)        liens existing on the Issuance Date and listed in Schedule 4(r) to the Note Purchase Agreement; and

(d)       Permitted Liens.

1.10     Transactions with Affiliates.  The Company will not pay, and will not permit any Subsidiary, directly or indirectly, to pay, any funds to or for the account of, make any investment (whether by acquisition of stock or Indebtedness, by loan, advance, transfer of property, guarantee or other agreement to pay, purchase or service, directly or indirectly, any Indebtedness, or otherwise) in, lease, sell, transfer or otherwise dispose of any assets, tangible or intangible, to, or participate in, or effect any transaction in connection with, any joint enterprise or other joint arrangement with, any Affiliate of the Company other than the Company or the Subsidiaries.

1.11     Notice of Defaults.  The Company shall notify the Holder promptly, but in any event not later than five business days after the Company becomes aware of the fact, of any failure by the Company to comply with this Article I.

3

ARTICLE II

EVENTS OF DEFAULT

2.1       If any of the following events of default (each, an “Event of Default”) shall occur:

(a)       Failure to Pay Principal, Interest, Etc.  The Company fails to pay any principal or interest or other cash payment amount when due hereunder or under any of the other Transaction Documents, whether at maturity, upon acceleration or otherwise, as applicable, and such breach continues for a period of five calendar days from the date thereof; or

(b)       Conversion and the Shares.  The Company fails to issue or cause to be issued shares of Common Stock to the Holder upon exercise of the conversion rights of the Holder within three Business Days after the due date therefor in accordance with the terms of this Note or fails to transfer any certificate for any such shares of Common Stock as and when required by this Note and the Note Purchase Agreement, as the case may be and either of such breaches continues for a period of ten business days after written notice thereof to the Company from the Holder; or

(c)        Breach of Certain Covenants.  The Company fails to comply with Section 1.1, 1.7 or 1.8, and such breach continues for a period of ten business days after written notice thereof to the Company from the Holder; or

(d)        Breach of Other Covenants.  The Company (i) fails to comply in any material respect with any other provision of Article I of this Note (other than Section 1.1, 1.7 or 1.8) and such breach continues for a period of fifteen calendar days after written notice thereof to the Company from the Holder or (ii) breaches in any material respect any other covenant or other term or condition of this Note or any of the other Transaction Documents (other than as specifically provided in clauses (a) and (b) of this Section 2.1 and subparagraph (iii) of this Section 2.1(d)), and such breach continues for a period of fifteen calendar days after written notice thereof to the Company from the Holder or (iii) breaches Section 5(c), 5(f) or 10(k) of the Note Purchase Agreement; or

(e)       Breach of Representations and Warranties. Any representation or warranty of the Company made herein or in any agreement, statement or certificate given in writing pursuant hereto (or pursuant to any Transaction Documents) shall be false or misleading in any material respect when made; or

(f)        Certain Voluntary Proceedings.  The Company or any Subsidiary shall commence a voluntary case or other proceeding seeking liquidation, reorganization or other relief with respect to itself or its debts under any bankruptcy, insolvency or other similar law now or hereafter in effect or seeking the appointment of a trustee, receiver, liquidator, custodian or other similar official of it or any substantial part of its property, or shall consent to any such relief or to the appointment of or taking possession by any such official in an involuntary case or other proceeding commenced against it or shall make a general assignment for the benefit of creditors; or

(g)       Certain Involuntary Proceedings.  An involuntary case or other proceeding shall be commenced against the Company or any Subsidiary seeking liquidation, reorganization or other relief with respect to it or its debts under any bankruptcy, insolvency or other similar law now or hereafter in effect or seeking the appointment of a trustee, receiver, liquidator, custodian or other similar official of it or any substantial part of its property, and such involuntary case or other proceeding shall remain unbounded, undismissed and unstayed for a period of 60 consecutive days; or

(h)        Judgments and Governmental Actions.  Any court of competent jurisdiction or any governmental authority shall enter one or more final non-appealable judgments against the Company or any Subsidiary or any of their respective properties or other assets, which find the Company or any Subsidiary liable for any damages or past due unpaid liabilities, including in respect of any unpaid taxes, including federal or state income, sales, use or other taxes, in an aggregate amount in excess of $100,000 not covered by insurance, and such judgment(s) remain unpaid for a period exceeding 15 days; or

4

(i)         Default Under Other Agreements. The Company or any Subsidiary shall default (after notice of default and lapse of any applicable grace period) on any of its obligations under any material mortgage, loan, credit agreement or other facility, indenture agreement, factoring agreement or other instrument under which there may be issued, or by which there may be secured or evidenced, any indebtedness for borrowed money or money due under any long term leasing or factoring arrangement; or

(j)         Fundamental Change.  A Fundamental Change shall have occurred;

then, upon the occurrence and during the continuation of any Event of Default specified in clause (a), (b),(c), (d), (e), (h), (i) or (j) of this Section 2.1, at the option of the Holder, and upon the occurrence of any Event of Default specified in clause (f) or (g) of this Section 2.1: (A) the Company shall pay to the Holder an amount equal to the outstanding principal amount of this Note plus accrued and unpaid interest on such principal amount to the date of payment plus accrued and unpaid Default Interest, if any, thereon at the rate provided in this Note to the date of payment, (B) all other amounts payable hereunder or under any of the other Transaction Documents shall immediately become due and payable, all without demand, presentment or notice, all of which hereby are expressly waived, together with all costs, including, without limitation, reasonable legal fees and expenses of collection, and (C) the Holder shall be entitled to exercise all other rights and remedies available at law or in equity, including any rights and remedies provided for in this Note and/or in any other Transaction Document.

ARTICLE III

DEFINITIONS

3.1       Certain Defined Terms.  (a) All the agreements or instruments herein defined shall mean such agreements or instruments as the same may from time to time be supplemented or amended or the terms thereof waived or modified to the extent permitted by, and in accordance with, the terms thereof and of this Note.

(b)        The following terms shall have the following meanings (such meanings to be equally applicable to both the singular and plural forms of the terms defined):

“Affiliate” means, with respect to any Person, any other Person that directly, or indirectly through one or more intermediaries, controls, is controlled by or is under common control with the subject Person.  For purposes of this definition, “control” (including, with correlative meaning, the terms “controlled by” and “under common control with”), as used with respect to any Person, shall mean the possession, directly or indirectly, of the power to direct or cause the direction of the management and policies of such Person, whether through the ownership of voting securities or by contract or otherwise.

“Applicable Rate” means twenty-one (21%) percent per annum.  If an Event of Default shall occur, then so long as any Event of Default shall continue, the Applicable Rate shall be the Default Rate (or, in any case, such lesser rate as shall be the highest rate permitted by applicable law).  

“Board of Directors” means the Board of Directors of the Company or a Subsidiary, as applicable.

“Business Day” means any day other than a Saturday, Sunday or a day on which commercial banks in the City of New York are authorized or required by law or executive order to remain closed.

“Common Stock” means the common stock, par value $.0001 per share, of Onstream Media Corporation.

“Company” shall have the meaning provided in the first paragraph of this Note.

“Conversion Amount” shall mean the outstanding amount of this Note (inclusive of principal and interest) on the Conversion Date.

“Conversion Date” means the date on which a Conversion Notice is given in accordance with Section 4.2.

“Conversion Notice” shall have the meaning provided in Section 4.1.

“Conversion Period” shall have the meaning provided in Section 4.1.

“Conversion Price” shall mean $.30 per share (subject to adjustment for any reorganizations, stock splits, dividends, distributions or other similar transactions occurring after the Issuance Date).

5

“Conversion Shares” shall have the meaning provided in Section 4.1.

“Default Interest” shall have the meaning provided in the first paragraph of this Note.

“Default Rate” means twenty-five (25%) percent per annum (or such lesser rate as shall be the highest rate permitted by applicable law).

“Event of Default” shall have the meaning provided in Section 2.1.

“Fundamental Change” means

(a)        Any consolidation or merger of any entity comprising the Company or any Subsidiary with or into another entity (other than a merger or consolidation of a Subsidiary into the Company or a wholly-owned Subsidiary), or the occurrence of any transaction or event in connection with which all or substantially all of the Common Stock shall be exchanged for, converted into, acquired for or constitute the right to receive consideration (whether by means of an exchange offer, liquidation, tender offer, consolidation, merger, combination, reclassification, recapitalization or otherwise), where the stockholders of any entity comprising the Company immediately prior to such transaction do not collectively own at least 51% of the outstanding voting securities of the surviving corporation of such consolidation, merger or other transaction immediately following such transaction; or the sale of all or substantially all of the assets of the Company or the Subsidiaries in a single transaction or a series of related transactions; or

(b)       The acquisition by a Person or entity or group of Persons or entities acting in concert as a partnership, limited partnership, syndicate or group, as a result of a tender or exchange offer, open market purchases, privately negotiated purchases or otherwise, of beneficial ownership of securities of the Company representing 51% or more of the (i) combined voting power of the outstanding voting securities of the Company ordinarily (and apart from rights accruing in special circumstances) having the right to vote in the election of directors or (ii) fully diluted shares of Common Stock.

“Generally Accepted Accounting Principles” or “GAAP” for any Person means the generally accepted accounting principles and practices applied by such Person from time to time in the preparation of its audited financial statements.

“Holder” shall have the meaning provided in the first paragraph of this Note.

“Indebtedness” as used in reference to any Person means all indebtedness of such Person for borrowed money, the deferred purchase price of property, goods and services (other than traditional trade payment terms up to ninety days or longer than ninety days, if consistent with past practice with respect to a particular supplier or vendor) and obligations under leases which are required to be capitalized in accordance with Generally Accepted Accounting Principles and shall include all such indebtedness guaranteed in any manner by such Person or in effect guaranteed by such Person through a contingent agreement to purchase and all indebtedness for the payment or purchase of which such Person has contingently agreed to advance or supply funds and all indebtedness secured by mortgage or other lien upon property owned by such Person, although such Person has not assumed or become liable for the payment of such indebtedness, and, for all purposes hereof, such indebtedness shall be treated as though it has been assumed by such Person.

“Issuance Date” means September 21, 2015.

“Maturity Date” means October 15, 2015.

“1933 Act” means the Securities Act of 1933, as amended.

“Note” means this instrument as originally executed, or if later amended or supplemented in accordance with its terms, then as so amended or supplemented.  

“Note Purchase Agreement” means the Note Purchase Agreement, dated as of September 21, 2015, by and between the Company and the Holder.

“Permitted Indebtedness” means

(1)        Indebtedness outstanding on the Issuance Date prior to issuance of this Note on the terms existing on the Issuance Date and listed on Schedule 4(l) to the Note Purchase Agreement;

(2)        Indebtedness evidenced by the Note;

6

(3)        Indebtedness incurred after the Issuance Date which is unsecured, subordinated to this Note in all respects as evidenced by a subordination agreement signed with Holder (Holder’s signature not to be unreasonably withheld), would not impair the Company’s ability to make payment on this Note pursuant to its terms and for which no payments of principal are permitted, whether at maturity or upon acceleration or otherwise, so long as this Note is outstanding;

(4)        endorsements for collection or deposit in the ordinary course of business;

(5)        in the case of any Subsidiary, Indebtedness owed by such Subsidiary to the Company;

(6)        an increase in the Thermo Credit, LLC Indebtedness secured by the accounts receivable of the Company and/or its Subsidiaries, provided such increase is on comparable terms to that certain Amended and Restated Loan Agreement, dated December 27, 2011 with Thermo Credit, LLC; or

(7)        Indebtedness in connection with Revenue Sales up to $1,000,000 (provided that net proceeds to the Company as a result of Revenue Sales, regardless of how accounted for by the Company, shall be considered Indebtedness for the purposes of this definition);

so long as at the time of incurrence of such Indebtedness no Event of Default has occurred and is continuing or would result from such incurrence and no event which, with notice or passage of time, or both, would become an Event of Default has occurred and is continuing or would result from such incurrence and so long as in the case of such Indebtedness referred to in the preceding clause (3) and (6), inclusive, such Indebtedness shall have been approved by the Board of Directors prior to the incurrence thereof.

“Permitted Lien” means the individual and collective reference to the following: (a) liens for taxes, assessments and other governmental charges or levies not yet due or liens for taxes, assessments and other governmental charges or levies being contested in good faith and by appropriate proceedings for which adequate reserves (in the good faith judgment of the management of the Company) have been established in accordance with GAAP; or (b) liens imposed by law which were incurred in the ordinary course of the Company’s business, such as carriers’, warehousemen’s and mechanics’ liens, statutory landlords’ Liens, and other similar liens arising in the ordinary course of the Company’s business, and which (x) do not individually or in the aggregate materially detract from the value of such property or assets or materially impair the use thereof in the operation of the business of the Company and its consolidated Subsidiaries or (y) are being contested in good faith by appropriate proceedings, which proceedings have the effect of preventing for the foreseeable future the forfeiture or sale of the property or asset subject to such Lien.

For value received _________________________ hereby sell(s), assign(s) and transfer(s) unto ______________________________ (Please insert social security or other Taxpayer Identification Number of assignee:  ______________________________) the within Note, and hereby irrevocably constitutes and appoints _________________________ attorney to transfer the said Note on the books of the Company, with full power of substitution in the premises.