Multi Window support is much improved with developer preview 2 for one very specific reason: Videos don't stop...

Originally shared by Andreas Proschofsky

Multi Window support is much improved with developer preview 2 for one very specific reason: Videos don't stop anymore if you change focus to the other side. This also means that you can now let any video run in the background (audio only) while you look around for another app on the home screen - which might not be the intended usage but it's still pretty nifty.
To clarify: While looking around the home screen in multi-window mode the primary window is shifted to the very edge of the display and only hinted at through a few pixel rows on the side.