title: Use waitKey in order pause and play video
body: <p>I have a <code>VideoCapture</code> in OpenCV, I can successfully display a given video. What I want to do now is to pause and play by pressing a key (optional which one as long as it works). I have been reading about <code>waitKey</code> but there is something about this whole thing I don't get (ASCII) and how to bind keys. What I understand it is used to let <code>highgui</code> process but can also be used for other purposes?</p>
  
  <p>If it is hard/impossible to pause a video and start it again I would be happy with just a delay when key is pressed. </p>
  
  <p>Help is much appreciated!</p>