There's been a bunch of threads on this over at /a/ but This is relevant enough here that it's probably worth a thread. With Youtube's recent introduction of Youtube Red, a bunch of videos with /m/usic in them are being blocked in the US and will probably affect Europe and other areas later. Keep in mind that it's not Bamco, Sunrise, Gainax or whatever company that owns the song doing it but Google.

Some things I've noticed that have been blocked today include:

OSTs:
https://www.youtube.com/watch?v=n2rVnRwW0h8
https://www.youtube.com/watch?v=pEx1D2lhKQA

OPs/EDs
https://www.youtube.com/watch?v=A358-QODoI0
https://www.youtube.com/watch?v=s7_Od9CmTu0
https://www.youtube.com/watch?v=M5i3H-mgoTE

Parody videos
https://www.youtube.com/watch?v=POmIkMdWmjk

This seems to be different than the usual taking down X for copyright infringement, this is affecting videos that've been on youtube for years now with no problem and it's all at once. Keep an eye out for anything that's blocked.