<amp-video controls
  width="640"
  height="360"
  layout="responsive"
  poster="images/kitten-playing.png">
  <source src="videos/kitten-playing.webm"
    type="video/webm" />
  <source src="videos/kitten-playing.mp4"
    type="video/mp4" />
  <div fallback>
    <p>This browser does not support the video element.</p>
  </div>
</amp-video>