Why would I want to play a video I can see only at 1/2 or 1/3 of the original size? Or I can't see at all (when in other view/application)? To drain battery? Swipe UX is designed to simplify tasks you do many times a day. Everytime I want to check something on the web while I am watching something, I have to pause video, change window/workspace, and so on... The question is: why NOT to pause video automatically when I want to switch activity? It makes sense to me. If your reason is only to show how awesome is real multitasking on N9, then try to think more pragmatically.