Availability on the Internet is not permission to use
A music, photo or video can be viewed publicly; This does not mean you have the right to use it in your own commercial video. Citing sources alone does not replace permission. Check who has licensed the asset you will use and under what conditions. Don't rely on a universal time rule like 'I'll be fine if I use it for a few seconds'. Even if you took the shot, the background music, location content or the appearance of another work may require separate evaluation.
A simple rights tracking table
List the music, stock footage, photos, fonts, and imported animations used per video. Write the source, license type, purchase or download date, scope, and document location on each line. Please also review the terms of the license for reuse or distribution in content that the sponsor will use in its own advertising. Remember that 'copyright-free' does not mean free and unlimited use under all circumstances. Verify the scope of the plan you're using and the account or project the license applies to.