It doesn't seem feasible to be programming these to dance by programming all individual actuator movements - there's got to be a separation of goal and execution, and somewhere in the execution the foot placement and force is tweaked to keep balance. Inverted pendulum bots do the same thing on easy mode with wheels. A simple inverted pendulum bot is something easy to do with a PID controller and much harder to control with scarequotes AI and machine learning. I'm sure some high schoolers have done it by now. I found this interview with Boston Dynamics CEO from 2019, which is mostly just fluff but it seems like they're going with "AI" for the low level reflex-type movements. Personally I have to say the dog-type robots are farther along the uncanny valley - the humanoids have a "chair-shaped-ass" leg and hip posture that isn't threatening and it's hard to dance with such an underdeveloped booty.“I break AI down into two parts. I call it athletic AI and scholarly AI. We’re kind of experts at athletic AI