title: how to detect change in playbackrate value (1x,1.5x ,2x) in video js..
body: <pre><code>videojs.player().playbackRate();
  </code></pre>
  
  <p>it gives me the current value of playbackrate... 
  but how to get changed playbackRate value onclick in PlaybackRateMenuButton??</p>
  
  <p><a href="http://docs.videojs.com/docs/api/playback-rate-menu-button.html#MethodshandleClick" rel="nofollow">PlaybackRateMenuButton Handle click</a></p>