I've clocked many hours into After Effects, but seeing this in a browser and _interactive_ is amazing. Never would I have thought that JS and browsers would progress so much in such a short period of time.
OTOH, it's mainly possible because computers are faster so Javascript isn't a slow language anymore, and the document model is just getting out of the way and letting you manipulate pixels directly.
This isn't manipulating the pixels directly. Javascript is still way too slow to do that, and I don't think that will ever change. The real work is done by the graphics card. The Javascript only uploads a frame to the graphics card, makes it run a shader and then displays the adapted frame.
