There is no set rule for the number of words or seconds you may use of a copyrighted work to fall under the fair use protection.

Question

Quizplus · Accepted Answer

Fair use is determined on a case-by-case basis and considers various factors such as the purpose and character of the use, the nature of the copyrighted work, the amount and substantiality of the portion used, and the effect on the potential market for or value of the work. There is no strict rule or guideline for the number of words or seconds that can be used without permission.

There Is No Set Rule for the Number of Words