index.html

<video autoplay="autoplay" muted playsinline="playsinline" class="video">
	<source src="/static-assets/video/cats_1.mp4" type="video/mp4">
</video>

<button id="simple-clone">Clone video without inserting</button>
<button id="clone-and-insert">Insert video (or clone and insert ) after original one</button>

<script>
	var cloneBtn = document.getElementById('simple-clone');
	var cloneAndInsertBtn = document.getElementById('clone-and-insert');

	var elem = document.querySelector('video');
	var clone;
	var cloned = false;
	var inserted = false;

	cloneBtn.addEventListener('click', function (evt) {
		evt.preventDefault();
		if (cloned) { return false; }
		clone = elem.cloneNode(true);
		cloned = true;
	});

	cloneAndInsertBtn.addEventListener('click', function (evt) {
		evt.preventDefault();
		if (inserted) { return false; }
		clone = clone ? clone : elem.cloneNode(true);
		clone.classList.add('cloned');
		elem.parentNode.appendChild(clone);
		inserted = true;
	});

</script>