When I run it looking at developer tools (F12 in Chrome), the console says there is an error on line 42 of index.html. Looking at that line, there is a subtle closure error. “this” inside of the onloadedmetadata callback is NOT the same as “this” inside of the done callback. Therefore this.video does not exist in the onloadedmetadata callback, and this.video.play() fails because this.video is undefined.
I’m not clear if that is the specific error you’re referring to, and it doesn’t reproduce all of the codepen, but I suspect that is because the shaders, etc. are missing.