If your guess was "play Skyrim while on a treadmill — yes, sort of. The device you see in the video above is called the Omni, and it's a virtual reality/treadmill hybrid that allows you to walk and look around naturally in a game.
Well, as natural as "walking in place in a contraption while wearing glasses" can be.
Right now, it's just a prototype that uses the Kinect somehow. Still, pretty impressive and probably the single best reason to ever play Skyrim without fast travel (whether that be for weight loss or tourism). Not that the tech is limited to only Skyrim, of course.
Omni in Skyrim - with Kinect 2 (head sensitivity adjusted) [Virtuix Omni via PC Gamer]