Using someone elses footage for promo video legally?
Pascal the Gambler
You can, but you can also be sued by the owner of the footage and have to pay it all to them.
This is interesting but, depending on the clips you use and the sources you receive them from, compilations are generally protected as original content. The 10 second thing is kind of a myth originating from music copyright I believe, though I'm not sure. To make the compilation, you must be certain the clips are from public domain and not pirated in some fashion, definitely make your own edits, maybe try to fit in your own style of commentary, and perhaps a disclaimer if you really want to be safe. Chances are, "Travis Scott" would want the publicity that attracts viewers to the event and wouldn't pursue any sort of beef with you. As long as it isn't showing them in a light they don't agree with you have nothing to fear.
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Yes you can be legally paid, but you can be legally sued for using proprietary product you aren't licensed to use which can also put the people you sell it to at risk for the same liability if used commercially. Thus if you fail to disclose you had no permission to use the content, you are liable to both the owns of the content and the people whom you sold the video. But the real question is will you be sued? The odds are against it in a big way unless you (or your client) are profiting from it in a big way which is why small time youtubers are not constantly being sued.
What would happen is that if the person on the footage was upset they would contact you and tell you to stop.