<!DOCTYPE html>
<html>
<body>

<p>Click the buttons to create a VIDEO element, one with preload set to "none", and one with preload set to "auto".</p>

<button onclick="myFunction('none')">Video without preload</button>
<button onclick="myFunction('auto')">Video with preload</button>
<br>

<script>
function myFunction(p) {
    var x = document.createElement("VIDEO");
    x.setAttribute("controls", "controls");
    var y = document.createElement("SOURCE");
    y.setAttribute("src", "movie.mp4");
    y.setAttribute("type", "video/mp4");
    x.appendChild(y);
    var z = document.createElement("SOURCE");
    z.setAttribute("src", "movie.ogg");
    z.setAttribute("type", "video/ogg");
    x.appendChild(z);

    // Set the preload property:
    x.preload = p;

    document.body.appendChild(x);
}
</script>

<p><b>Note:</b> The preload attribute is not supported in IE.</p>

</body>
</html>