The best guess is that it's the new 5D III. By the size of the camera, it looks to be a full-framer. It's also interesting that the screen looks to be a 16x9 ratio (or something close to it), which is another hint that it's a camera intended to be used widely by independent filmmakers.

Even if the 5D's autofocus won't be as full-featured or as fast as that of the 1Dx or even the 7D, who's to say they weren't testing a newer/better Al Servo algorithm? They could still improve the 5D's autofocus while still leaving a performance gap compared to other cameras. We all know a 5D Mark II successor is in the works; the evidence suggests this is a small glimpse.