As per the title - weirdly, when airplaying content from the the TVNZ On Demand app, we need to leave the iPad's screen on (and programme to the foreground) for it to continue working. As soon as the cover's shut on the iPad the airplaying ceases.
This is exactly the same problem we had when the initial Lightbox app was released (before they removed Airplay).
Do other people have this problem, and can anything be done to fix it? Or is it a flaw in the app's design?