LayoutTests/media/video-muted.html

<video controls></video>
<p>Test 'muted' attribute<p>
<script src=media-file.js></script>
<script src=video-test.js></script>
<script>
    testExpected("video.muted", false);
    run("video.muted = true");
    testExpected("video.muted", true);
    video.src = findMediaFile("video", "content/test");
    run("video.load()");
    waitForEvent("canplaythrough", function () {
        testExpected("video.muted", true);
        run("video.muted = false");
        testExpected("video.muted", false);
        endTest();
    });
</script>