When you move the metronome and put on a table that moves multiple metronome that ticks all the metronome sound at the same time as it is known in sync eventually.
Create table test equipment such as works by hanging from the left and right units to put a metronome, the laboratory is Ikeguchi, we have conducted an experiment in sync. In this video 32 metronome ticks sound at the same time.
So, I think it's basically that they put it on a suspended and flexible surface so that they would eventually synchronize due to the movement through the table. Neat.
At 2 minutes they're mostly synchronized except for one that's going the opposite, but 41 seconds later it matches the rest.