title: Can I access custom html tag <component> or <slot> contents
body: <p>Let's say I want to create a custom html element such as:</p>
  
  <pre><code>&lt;video-container&gt;
    &lt;video&gt;&lt;/video&gt;
  &lt;/video-container&gt;
  </code></pre>
  
  <p>So I create a template like this:</p>
  
  <pre><code>&lt;div class="wrapper"&gt;
     etc..
     &lt;content&gt;&lt;/content&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Then I attach it to the page via an HTML Element Prototype <code>createdCallback</code>.</p>
  
  <p>Inside that callback I want to be able to attach listeners to the <code>video</code> element so I can do stuff on <code>play</code>, <code>pause</code> etc.. It's not clear to me if there is anyway to access the video tag passed in. I can get access to the <code>content</code> tag but it doesn't show any child nodes. Is this possible? </p>
  
  <p>I can access the video element if I just grab the whole document and get the video element but this is ugly because I want to be able to get only the video tag in the scope of the present custom element.</p>