It may be more advantageous to link to outside media rather than to embed it within your video. Discuss specifics with your instructional designer and producer.
Hyperlinking, including embedded hyperlinking, is lawful unless the linked material is clearly infringing.
What constitutes “clearly infringing”? Clearly pirated works; g., a full-length feature film/TV show uploaded by a random private user (instead of the movie studio/TV network) or a full scanned copy of a textbook on file sharing website.

Works in the public domain are not protected by copyright law and are freely available for use.
US federal government works are in the public domain.
Note: works from foreign governments and US state governments are not necessarily in the public domain.
Works published prior to January 1, 1923, are in the public domain.
A copyright holder can waive her copyright over a work and throw the work into the public domain.
Academic concepts, theories, formulas, and objective facts are unprotected under the copyright law, freely available for use.
Where to find public domain works
https://pixabay.com /
https://www.pexels.com/public-domain-images /
https://wikimedia.org/wiki/Main_Page
https://www.flickr.com/ (in license dropdown menu, under “No known copyright restrictions” and “US Government works”)
- https://unsplash.com/
- Some items from the New York Public Library – https://www.nypl.org/research/collections/digital-collections/public-domain
- Some from Pond5 – https://www.pond5.com/free

Works licensed under Creative Commons are freely available for use.
Creative Commons is an open licensing scheme. The authors retain formal copyright while allowing use by others without specific permissions from the authors.
To use a Creative Commons work, you are mainly required to provide citations.
Where to find Creative Commons works
Google Image Search (Click “Tools” and in “Usage rights” dropdown menu, under any of those four licenses.)
https://doaj.org/
https://search.creativecommons.org /
https ://commons.wikimedia.org/wiki/Main_Page
https://www.flickr.com/ (in license dropdown menu, under “All creative commons”)