I can still watch a video but anything else won't load, like there's nothing on the screen except the video, no title, no description, no comments, no recomendations, nothing.
Yeah it's gone for me. I just get gray thumbnails and 404's. I actually freaked for a moment that the person I was subscribed to just had their videos all purged.
It turns out that YouTube going down completely breaks YouTube Music. You can't play downloaded songs because it tries to connect, fails, and then seems to de-authorize your account?