MPMoviePlayerController not working in iOS 5 xcode (with storyboard), but works perfectly in iOS 4

I'm having problems playing a movie with the new xcode that comes with iOS 5 beta. I created a simple project (with storyboards and all), and added this code to a button:

MPMoviePlayerController *moviePlayer;
 NSString *path = [[NSBundle mainBundle] pathForResource:@"position" ofType:@"m4v"];
 NSURL *videoURL = [NSURL fileURLWithPath:path];
 moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:videoURL];
 //[moviePlayer setControlStyle:MPMovieControlStyleDefault];
 [moviePlayer.view setFrame: self.view.bounds];  // player's frame must match parent's
 [self.view addSubview: moviePlayer.view];
 [moviePlayer prepareToPlay];
 [moviePlayer play];
 

The confusing thing is that it works perfectly when I throw the code into a project built with a previous version of xcode (specifically the one that comes with iOS 4.3).

Any ideas?

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