chromium/third_party/blink/web_tests/media/video-source-type.html

<!DOCTYPE html>
<title>Test "source" element "type" attribute.</title>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<video>
    <source src=content/error.mpeg type=video/blahblah>
    <source src=test.mp4 type=video/x-chicken-face>
    <source src=test.ogv type=audio/x-higglety-pigglety>
    <source src=content/test.ogv type=video/ogg>
    <source src=content/error2.mpeg type=video/mpeg>
</video>
<script>
async_test(function(t) {
    var video = document.querySelector("video");

    video.onloadstart = t.step_func_done(function() {
        var url = video.currentSrc;
        assert_equals(url.substr(url.lastIndexOf("/media/") + 7), "content/test.ogv");
    });
});
</script>