title: When using video.js, why doesn't the full-screen button work inside an iframe?
body: <p>I use video.js for video play. When <em>not</em> using an iframe, clicking the full screen button works as expected. However, when using an iframe, the full screen button doesn't work. Why is this?  </p>
  
  <p>The homepage of video.js is <a href="http://videojs.com/">http://videojs.com/</a></p>
  
  <p>the code of iframe page is:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;Demo&lt;/title&gt;
    &lt;meta http-equiv="Content-Type" content="text/html; charset=gb2312"&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;iframe src="sco01-m.htm" id="cw" name="cw" width="100%" height="1000px;"        scrolling="no" frameborder="0"&gt;&lt;/iframe&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>the code of sco01-m.htm page is:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;Demo&lt;/title&gt;
    &lt;meta http-equiv="Content-Type" content="text/html; charset=gb2312"&gt;
    &lt;link href="http://vjs.zencdn.net/c/video-js.css" rel="stylesheet"&gt;
    &lt;script src="http://vjs.zencdn.net/c/video.js"&gt;&lt;/script&gt;
  &lt;body&gt;
    &lt;div align="center"&gt;
      &lt;video id="my_video_1" class="video-js vjs-default-skin" controls
        preload="auto" width="800" height="600" poster="1.jpg"
        data-setup="{}"&gt;
        &lt;source src="A-2-4.mp4" type='video/mp4'&gt;
        &lt;source src="oceans-clip.webm" type='video/webm'&gt;
      &lt;/video&gt;
    &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>The sco01-m.htm page can use the fullscreen button, But the iframe page can't use.</p>