title: Playing a video with python cv2
body: <p>I'm trying to play an <code>avi</code> file with python cv2</p>
  
  <pre><code> cap = cv2.VideoCapture('lot1.avi')
  </code></pre>
  
  <p>but the <code>cap.isOpen()</code> is always <code>False</code>.
  Dose it have to do with the file type? do I have to install somthing?</p>
  
  <p>Thanks... </p>