JS Rockin Out Webcam V2

<body bgcolor="black">
<video id="video" autoplay hidden>
</video>
<canvas id="canvas" width="500" height="500" style="border:0px solid">
<script>
var video = document.getElementById("video");
var c = document.getElementById("canvas");
var ctx = c.getContext("2d");
var i=0;
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var video = document.getElementById('video');
var mediaConfig = { video: true,audio:true};
navigator.mediaDevices.getUserMedia(mediaConfig).then(function(stream) {
video.src = this.window.URL.createObjectURL(stream);
video.play();
  video.addEventListener("play", function() {i = window.setInterval(function() {
ctx.drawImage(video,Math.random()*-40,Math.random()*-40)},0.1);
}, false);
});
</script>