I had to reload the demo once or twice to get the features to work, once they did, wow. It is a little overwhelming but an effective demo. I used the latest beta of Firefox 4.
The video in question is well worth watching in its own right. It and Web Made Videos a project made under the auspices of Mozilla’s Drumbeat initiative. Drumbeat specifically aims to pull in all kinds of people, not just techies, to build on and highlight what is possible with the open standards of the web. The film maker responsible for the demo page is Brett Gaylor, one of my favorites for his “RIP: A Remix Manifesto” documentary.