Interesting. The issue occurs because I have WebGL disabled, causing the createShader function you're using to throw an error. You can reproduce this by going to chrome://settings, disabling "Use hardware acceleration when available," refreshing the page, and then triggering the same error.
The model tries to copy the blinks of the original video so it's possible that in other conditions, you'd notice less of this.
Fun to see this feedback though, definitely something worth improving :)