Would be cool to build one of these in real life! Doesn't seem that hard to build, perhaps hard to calibrate though.
The seems to have something that stops the end of it moving on until enough tension has built up to side underneath it. That much is fair enough. But then that same thing stopping the end would also prevent the same satisfying wiggle when it gets to the next position because it overshoots immediately.
The only thing I can think of is that the restraining pins move in and out is the clock have at just the right time but that would be quite a fiddly implementation and probably affect the visuals