They do use keyframes most likely captured from a human controller. you can see this after they do the backflip at :29s they land a bit differently and recover in slightly different ways but all end up in a static pose for a moment before moving on to next movement. The advancement here is the dynamics to go between those frames. Looking at last years performance you can see they pretty much go from frame a to b then stabilize then to c then stabilize. This is what makes this years look much more lifelike there seems to be some active stabilization going on during the movements. It also seems to let them chain movements that can take advantage of momentum much better rather than needing to be at rest between frames.