title: Add custom headers to videojs player source
body: <p>I have a backend api (using express) that handles a streaming video m3u8 file.</p>
  
  <pre><code>http://localhost:3000/api/stream.m3u8
  </code></pre>
  
  <p>This endpoint will only work with a proper user <code>token</code>. </p>
  
  <p><strong>router</strong></p>
  
  <pre><code>router.get('/api/stream.m3u8', controller.stream);
  </code></pre>
  
  <p><strong>controller</strong></p>
  
  <pre><code>exports.stream = function(req, res) {
     var token = ''; // ? not sure how to get access to a sent up token
     if (!token) res.status(401).json('Not authorized');
     // if token is valid, proceed
  };
  </code></pre>
  
  <p>On the front end, I am using videojs.</p>
  
  <pre><code> var player = videojs('my-player', {})
  
   // set source to my backend api m3u8 file
   player.src({
      src: 'http://localhost:3000/api/stream.m3u8',
      type: 'application/x-mpegURL'
    });
  </code></pre>
  
  <p>Is there a way to add a custom header to the videojs plugin to send up data to my backend?</p>