What do you mean by rendered with pure JS? It's rendered server side, isn't it?
I'd still like to see a demo page with their JavaScript decoder.
So, it's some client JS WebGL code, and something else driving the encoder in the cloud
I like the idea of scriptable VNC like streams.
You can read more about it here -> http://www.otoy.com/130501_OTOY_release_FINAL.pdf