Apple made significant changes to the MPMoviePlayerController API:s in iOS 3.2. Before, all you had to do was to initialize the MPMoviePlayerController and call play. Now things are a bit more complicated because videos can be played on a portion of the screen (good for the iPad) and not just in full screen mode.
Read more on Play Video with MPMoviePlayerController in iOS 3.0 and 3.2/4.0…