chromium/content/test/data/accessibility/event/text-selection-inside-video.html

<!DOCTYPE html>
<html>
<body>1<video id="video">2</video><div id="div">3</div>
<script>
  function go() {
    document.execCommand("selectAll", false);
    document.getSelection().extend(document.getElementById("video"), 0);
    document.getSelection().extend(document.getElementById("div"), 0);
  }
</script>
</body>
</html>