or even better, if I upload a video to YouTube and it includes a Nirvana song, and if YouTube has permission from Interscope to distribute Nirvana music by virtue of an explicit license or the fact that Interscope uploaded a bunch of Nirvana videos, since it's YouTube doing the distributing shouldn't their licenses cover all? Don't even bother technically under the hood digging up the licensed copy

Obviously they don't, but they should