osu! b658.test
Videos don't seem to work at all for me anymore.
In "Funtastic Power! - This is Sparta REMIX" (ranked) the music started playing, but the screen froze, and the PC lagged so bad I had problems closing osu! - it took me several minutes just to get task manager open. It doesn't fail the song or anything - it just keeps going. It is worth noting that once, it did fail the song after freezing, and osu! still worked fine, but when I started the same song again without restarting osu! and let it run to the end, osu! crashed with an error message (not the crash reporter).
In "Caramell - Caramelldansen (Speedycake Remix)" (ranked) the video showed a few frames, then went back to the skin background. No lag at all.
It seems likely to me that the ffmpeg integration has something to do with it, as it worked fine before that.
EDIT: It seems that videos do work - but only on some songs. osu! just crashed in the middle of a song with a video (with the error reporter), however the video worked fine up until that point.