[shanebellone]

It does sound like it, but no it's just plain JS. I recorded a short clip; showing is better than attempting to explain.

Edit: It is almost AJAX. The more I think about it the more the boundaries get blurry. Essentially, it's AJAX that does not fetch or receive resources directly. It interacts with a buffer that holds JSON which describes the next batch of cards. The images are streamed via <img> tag, so the buffer is small relative to the media it represents.

https://www.youtube.com/watch?v=6eSDuAe3pHA