As a web developer and web user I completely refuse to tell you, otherwise I worry you might copy this horrendous site design elsewhere.
This is a site anti-pattern (at least at desktop resolution). The site is only readable when I shrink the browser down until that terrible animated nonsense goes away.
HTML5 video, I'm sure. They used that on the Mac Pro website too - they had two videos for each 'image', one forward, and one in reverse. Some JS playback controls linked to scrolling, and that's pretty much it. Very nice results though.
It's a series of images and videos is looks like. The video plays and then overlays an image (in the exact location that the video ended) on each scroll/navigation.
This is a site anti-pattern (at least at desktop resolution). The site is only readable when I shrink the browser down until that terrible animated nonsense goes away.