They're using a Kuka DLR lightweight arm. It's a rather high-end piece of equipment. It's strong enough to do a pull-up, fast enough to catch a ball, and every

They're using a Kuka DLR lightweight arm. It's a rather high-end piece of equipment. It's strong enough to do a pull-up, fast enough to catch a ball, and every joint incorporates a six-axis force-torque sensor. It's definitely strong enough to do damage. Of course, that just means that Kuka loaded it up with safety systems. The FT sensors let it know exactly how much force it's applying, and if they read too high a value the brakes slam on. I've never worked with those arms before, but I'd bet that there's a similar system completely in hardware. You'll also notice that the operator's left hand and the entire back half of the room are never seen; there are at least two emergency stop buttons there, probably more, and one of them is wired directly the arm's power supply. Really, though, all that engineering is of secondary interest. That look on her face is exactly why I got into robotics. And we've only been at it for 15 years; imagine what we'll be able to do in another 15.