It seems that Apple has changed the way that it handles video playback in iOS 4. In previous iPhone OS releases, you merely initialized the movie player instance and then hit play. iOS 4 is slightly more complicated because it no longer presumes that all video playback will be fullscreen, or even that there will only be one video on the screen at a time. So here is the code to get the old behavior:
MPMoviePlayerController* thePlayer = [[MPMoviePlayerController alloc] initWithContentURL: [NSURL URLWithString: trailerURL]]; thePlayer.scalingMode = MPMovieScalingModeAspectFill; thePlayer.view.frame = self.view.bounds; [self.view addSubview: thePlayer.view];[thePlayer setFullscreen: YES animated: YES];
I ran into this when I was updating an app from 3.0 to 4.0. When you clicked on the button to play the video, rather than playing a video, nothing happened, and then a few seconds later only the audio would start playing. I had listed in my code the URL for the docs from Apple which I had used, and verified that it was correct - I had no idea that the document itself was out-of-date! It was quite a problem for me, and at first I thought it was a bug in my code. Later I learned that Apple updated their API, but not all their docs. Anyway, hope this helps someone.