LayoutTests/media/video-src-set.html

<video controls></video>
<div>Test that setting src attribute triggers load</div>
<script src=video-test.js></script>
<script>
    video.setAttribute('src', 'content/test.mp4')

    waitForEvent('loadstart', function () {
        testExpected("relativeURL(video.currentSrc)", "content/test.mp4");
        endTest();
    } );

    video.setAttribute('src', 'content/test.mp4')
</script>