missing. -->
  <amp-youtube data-videoid="https://www.youtube.com/watch?v=dQw4w9WgXcQ">
  </amp-youtube>
  <!-- This is invalid, one can only have one of these two. -->
  <amp-youtube width="480" height="270"
               video-id="https://www.youtube.com/watch?v=9bZkp7q19f0"
               data-videoid="https://www.youtube.com/watch?v=dQw4w9WgXcQ">
  </amp-youtube>
</body>
</html>
