Before we hit Retina, we scrape out a fancy fan. These blades are supposedly super quiet due to their asymmetrically spaced blades.

Interestingly enough, while Jony Ive was jazzed about "thinner, variably spaced fan blades," this tech has been included in certain MacBook Pro models since 2012.

There's also a significant amount of space not taken up by blades—that's probably another sick thermal system feature. Plus it looks nice in the video.

Likely a Texas Instruments motor controller on the fan flex cable