title: MPMoviePlayerContentPreloadDidFinishNotification does not fire [iPhone]
body: <p>I'm running into a problem with the MPMoviePlayerContentPreloadDidFinishNotification notification.
  I've regisered to recieve the MPMoviePlayerContentPreloadDidFinishNotification notification and MPMoviePlayerPlaybackDidFinishNotification but the first one never fires.
  Is this bug in Firmware OS 3.0 ? maybe fixed in 3.1 ? or ? Because my divice and similator is 3.0 maybe this is a bug ?</p>
  
  <p>My code :</p>
  
  <pre><code>...
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MovieDidLoad:) name:MPMoviePlayerContentPreloadDidFinishNotification object:nil];
  
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MovieDidLoad:) name:MPMoviePlayerPlaybackDidFinishNotification object:nil];
  ...
  -(void)MovieDidLoad:(NSNotification*)notification
  {
      UIAlertView *alert = [[UIAlertView alloc] 
                            initWithTitle:@"Notification Listener" 
                            message:@"Notification Listener invoked" 
                            cancelButtonTitle:@"Ok dude!" 
                            otherButtonTitles:nil];   
      [alert show]; 
      [alert release];    
  
  }
  </code></pre>
  
  <p>The MPMoviePlayerPlaybackDidFinishNotification is always fired but MPMoviePlayerContentPreloadDidFinishNotification is never fired.
  Any ideas ?</p>