Exhibit 5.1

February 4, 2015

SeaChange International, Inc.

50 Nagog Park

Acton, MA 01720

Re: Registration Statement on Form S-8 Relating to the Amended and Restated

2011 Compensation and Incentive Plan (the “Plan”) of SeaChange

International, Inc., a Delaware corporation (the “Company”)

Dear Sir or Madam:

Reference is made to the above-captioned Registration Statement on Form S-8 (the “Registration Statement”) filed by the Company on the date hereof with the Securities and Exchange Commission under the Securities Act of 1933, as amended, relating to an additional 2,500,000 shares of common stock, par value $.01 per share, of the Company issuable pursuant to the Plan (the “Shares”).

We have examined, and are familiar with, and have relied as to factual matters solely upon, a copy of the Plan, the Company’s amended and restated certificate of incorporation, as amended, the amended and restated by-laws of the Company, the minute books and stock records of the Company and originals of such other documents, certificates and proceedings as we have deemed necessary for the purpose of rendering this opinion.

Based on the foregoing, we are of the opinion that the Shares have been duly authorized and, when issued in accordance with the terms of the Plan and the terms of any agreement relating to any of the awards granted thereunder, will be legally issued, fully paid and nonassessable.

This opinion is limited to the Delaware General Corporation Law (which includes applicable provisions of the Delaware Constitution and reported judicial decisions interpreting the Delaware General Corporation Law and the Delaware Constitution) and the laws of The Commonwealth of Massachusetts, and we render no opinion with respect to the laws of any other jurisdiction.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement and to the use of our name in the Registration Statement under the caption “Legal Matters” in the prospectuses included as a part thereof. In giving this consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended, or the rules and regulations of the Securities and Exchange Commission thereunder.

Very truly yours,

/s/ Choate, Hall & Stewart LLP

CHOATE, HALL & STEWART LLP