chromium/third_party/blink/web_tests/http/tests/priorities/resources/preload/as-video.html

<script src="../common.js"></script>
<script>
  observeAndReportResourceLoadPriority(new URL('../../../resources/test.mp4', location));
</script>

<link rel="preload" as="video" href=../../../resources/test.mp4 type="video/mp4" onload="reportLoaded()" onerror="reportFailure()"></script>