It's not as awful as I would have suspected from the description, but I still don't really like it. Bar the fancy "scrollbar" timeline they give you to jump directly somewhere in the page - which does alleviate that problem I mentioned a little - it does feel exactly like infinite scrolling to me, I'm not sure where you're making the distinction between lazy loading and this. The content does physically appear later on the page, making the scrollbar jump around, which I heavily dislike. This renders the native scrollbar pretty much useless as a reference point.

The mobile preview is probably a nice touch, though.