I just started working on Windows 8 machine. If you open IE
app in tiles mode and play music (say on YouTube) and then switch back to work in
tiles mode and do something else, the music stops automatically.
The workaround I found is, go to Desktop mode, open IE, play
your YouTube music and come back to the tiles mode to work.
There has to be a way to play multiple instance of IE in the
background. I am sure Media Player works in the background.