Just put a div and update the content...
<script>
function setvideo(src) {
document.getElementById('div_video').innerHTML = '<video autoplay controls id="video_ctrl" style="height: 100px; width: 100px;"><source src="'+src+'" type="video/mp4"></video>';
document.getElementById('video_ctrl').play();
}
</script>
<button onClick="setvideo('video1.mp4');">Video1</button>
<div id="div_video"> </div>