And because of this, the person above is stepping on the "spinning surface" (the "base" surface of a cylinder) of these tiny disks, instead of the curved surface like a normal wheel or some industrial conveyor wheels (as someone linked below, https://www.youtube.com/watch?v=PRS0Uj2WdpA ).
So in a sense, they're not "rotating like rotating wheels" despite being wheels/disks.
BTW, it looks like they also can adjust its axis angle slightly (less than 30 degree), which I imagine is also crucial to how it works.