To play video in my app, I set MPMoviePlayerController and add it to subview. The user can change to full screen mode using pinch gesture.
In this viewController (that contains the Movie Player View), I set the viewWillDisappear to set objects to nil.
But, in iOS 6, when activating fullscreen mode the MPMoviePlayerController in the view controller that contains the Movie Player View calls the methods viewWillDisappear and viewDidDisappear.
In iOS5, those methods were not called.