So if I understand this correctly... YouTube took these videos down based on a copyright (DMCA?) claim. Which of course isn't a court ruling or anything. At the same time, no court would ever uphold this removal, because it obviously falls under "parody" which is protected. (Otherwise shows like Saturday Night Live couldn't even exist.) After all, the end result is no different from a really good vocal impersonator.…
You mean enforce? Youtube can remove whatever they want; they don't need to be in the right about it.