Yeah, a lot of the videos I've seen that never get removed have a lot of legal jargon mentioning the music is copyrighted and who the owners are. It mentions the music is being used under some "fair use act of 1976" or something along those lines. Apparently it allows individuals to use videos for education, dispersal, entertainment, etc. as long as it's not for profit.

Now they're put on youtube, and youtube makes money. So I don't know how legit it is, but the videos don't get removed. At least not yet.