If you obtain permission (the legal term is a "license"), you can use another person’s copyrighted works as they’ve permitted. Section 1 of our Community Guidelines discusses this.
If your use of the material is protected by fair use, you don’t need the copyright holder's permission.
Here are some more options for using content from other videos for your own:
- Creative Commons, where creators apply for a license on their videos for re-use provided it's used according to the license's terms.
- The Editor, which includes templates and stock images and video footage to create engaging social videos.