title: iOS: Getting content of video frame at each frame during playback
body: <p>Here's the thing: in my iPad app I'm playing a video using MPMoviePlayerController, the movie player's view is a subview of my main view and I have another semi-transparent view on top of the video view.</p>
  
  <p>What I'd like to do is redraw my transparent view every time the video view is updated, because the content of that view depends on the video, so I need to know when it is updated.</p>
  
  <p>Furthermore, I need to get the content of the video view as an UIImage in order to update my transparent view.</p>
  
  <p>Anybody has any idea on how to do these two things?</p>
  
  <p>Thanks a bunch</p>