JSFiddle - React, Tailwind, and code Playground

HTML

<template id="shadowtree">
  <video controls style="width:640px;height:360px;">
      <content></content>
  </video>
</template>
<div id="host">
    <source src="http://www.html5rocks.com/en/tutorials/video/basics/devstories.mp4" type="video/mp4" />
</div>

JavaScript

var shadowRoot = host.createShadowRoot();
var clone = document.importNode(shadowtree.content, true);
shadowRoot.appendChild(clone);