It's possible to do video rates on e-ink. Epson make some very good chips like the S1D19120 or S1D13M01. How they've managed this in this form though, I'm not at all sure. Time to do some digging.
Looking at the video I was about to buy one because of how good it looked but yeah you are right. There is no way that can be real for so cheap.
It also refreshed with no ghosting without doing the full black/full white page clear. Either e-ink has come a massive way since I bought my kindle last year or it's a mockup.
The page states they are "working closely" with E-Ink Corp., and even plan to have color versions by 2014, so maybe they're just showing off the most recent tech (which may or may not end up in the actual gadget).
Color E-Ink is notorious vapourware, planned for production since 2010.
Looks awesome, but I wish they showed me photos of the actual case details (side view - does it make the phone much thicker, and bottom view with charger)