Thats cool, havnt seen it before!
i can't tell you what's going on at all.
all i can suppose is that each individual metronome is pushing left or right on the table surface.
it reasonable to assume that at anyone instant there'll be more pushing right than left or visa versa. then more left than right, at some frequency which is related to the combination of each individual frequency
(keep an eye on metronomes 2,4,5 at point at which they are placed on rollers)
once the surface is allowed to move (place on rollers) the surface will begin to move at this combined frequency, and the metronomes which are out of phase with the surface will experience some kind of retardation/phase shift until they are in sync with the surface (eachother),
of course they will naturally try to return to their own specific frequency (as you can just about see in the vid) but this deviation increases the force they feel to keep them in step.
thats just my initial guess anyhow.
btw.. are metronomes powered? or will they stop of their own accord?
i'm guessing theese ones are powered somehow, which is why they don't cancel each other out a bit more when placed on the rollers!
also is there a significance to the odd number of metronomes>?
looking forward to a better explanation!:)
jim
edit:woohoo, just reached 100posts (only took 2+ years!)