This is a pretty nifty illusion: as you look at a spot between two rapidly changing images of faces, your brain distorts the images, making them look really weird:
I could do without the title they chose for the video, but the paper on which it's based is called "Flashed face distortion effect: Grotesque faces from relative spaces", which may not explain much, either. What it means, basically, is that as the faces flash, certain features get distorted by your brain, and the amount of distortion depends on how much that feature deviates from the rest in the set. In other words, someone with slightly larger eyes gets perceived by you as having huge eyes. Go ahead and pause the video and click through it; the faces are pretty much normal faces, so the distortion really is an illusion.
I think that's pretty neat; I'm fascinated by how our brains perceive faces in particular, since people see them everywhere. I'd love to see some variations on this, like showing men's faces, or a man on one side and a woman on the other. Would it work for animal faces too? Hmmm.
I'll note that some people have a hard time seeing this illusion; my friend Richard Wiseman -- who knows a thing or two on how the brain can be fooled! -- doesn't see it well. Do you?
Tip o' the Nacker cube to Gizmodo and my old friend Bill Dalton.