A very nice site which allows you to scroll through/into a video... I can't read a word of it tho.
And cool it's not Flash - it's using jQuery and HTML5 etc. so it's for those modern browsers.
A good example of a 404 page, this one uses the parallax effect.
https://github.com/jquery/jquery/tree/trunk/plugins/color/404
Perhaps all website designs should have a hidden page like this, it's an opportunity for some creativity. It's a bit like those old Easter eggs you might find in a program/website.
Here's some more hidden creativity... http://news.cnet.com/8301-17939_109-9976422-2.html