I love the idea, but they've made an odd choice in the way they've styled the page: I can't scroll down to read all the text. Page scrolling is jerky and the text disappears for me before I reach the bottom of the text. I had to inspect the page source to finish reading "How does it work?"
I was also using chrome stable, Mac OS 10.8. The left column doesn't disappear when I scroll down in Firefox (although also much more jumpy than I'm used to). But, I guess it seems to only affect me. I do have a retina display and they are using javascript to serve me retina images, which might have something to do with it.
