Most of the time the video is just a blank white or grey screen.
It doesn't play audio or video.
Some videos work, though.

It happens in all music rooms.
I'm using the Steam version.

don't use steam standalone if you wanna play videos
use google chrome instead

Okay. Does the regular .exe standalone work, though? Or do I have to use the browser?

Edit: Apparently there's already a thread about this. http://atelier801.com/topic?f=6&t=818635
Sorry about that. BTW, someone's saying that it still doesn't work in Chrome. I'll try, though.

I'm going to go ahead and lock this thread since you can talk about this issue there. My Steam standalone works fine, so give more information in the thread that I linked (and you found~), such as what operating system you have. My boyfriend had an issue with the Steam standalone that resolved when he upgraded from Windows 8 to Windows 10.