I had trouble with a video file that didn't play when music was played in a previous layout. Although, the video file played when I launched the only layout with the video file included.
I wanted to see if for some reason access to the video file (via direct localhost:50000/myvideo.mpg) is still given after a go to layout command is "issued" from a previous layout. But, I didnt know where the myvideo.mpg file was located.
Anyway, to make a long story short. It turns out that the problem went away when i switched from Chrome to IE, and the problem went away.
I think music and video is probably not consistently supported across browser.