OK, I've just tried You Tube at the same time as listening to Media Player. Both continued to give me (blended) audio no matter what combination I tried of having the windows in the foreground/background/minimized/maximized. This is on OS2008 using the MicroB browser.

So the problem you are seeing may be specific to your apps... maybe it is Pidgin, or maybe you are running Opera/OS2007? Whatever it is, I wasn't able to duplicate the problem on my N800.