Since other people have asked me if I can add music to my "Time & Weather" screensaver I thought I'd bring it up here. Now that I've read the documentation , I see it's not allowed. I can see reasons why it might not be a good idea, but it there any other technical reasons why it's not allowed?
It's an implementation quirk about the way the screensaver interacts with the active application and routing events and messages appropriately. We took some shortcuts here (including disallowing audio in the screenserver) in order to finalize v2.6 quickly and get it in your hands.