title: Crop video from QTKit
body: <p>I'm using the OSX QTKit sample code from here: <a href="http://bit.ly/mAaHGI" rel="nofollow">http://bit.ly/mAaHGI</a></p>
  
  <p>I'd like to crop the video, both on the screen and the saved file, to simulate different aspect ratios. What is the best way to do this?</p>