title: addEventListener in content script not working
body: <p>I've got a chrome extension with a popup.html and an injected content script. With the injected content script I'm trying to access youtube's javascript API functions and it all works fine except for one: addEventListener.</p>
  
  <p>The event listener of Youtube's javascript API listens for the state of the video to change. So if the end of the video is reached the state changes to 0. </p>
  
  <pre><code>var currentVideo = document.getElementById('movie_player');
  currentVideo.addEventListener("onStateChange", "onytplayerStateChange");
  
  function onytplayerStateChange() {
     console.log("The state of the player has changed");
  }
  </code></pre>
  
  <p>This piece of code works just fine in a normal environment but it fails to work in content script. Why can't I catch changing events in my content script? Any ideas?</p>