It looks to me like that system has one of the rider's bindings anchored to the board. The mechanism in the middle is just providing damping. The thing in the middle is a lever driven by the plate-to-board distance, which in turn drives a damper that runs from the center mechanism to the front binding.
Originally Posted by nekdut
It seems to me that if the plate stays flat, and the board bends, there are two options:
(a) the distance between the center of the plate and the center of the board has to increase, or
(b) the distance between the board and the tips of the plate has to decrease
If you attach one binding solidly and let the other slide, like Sean's plate, you have (a). If you attach the center solidly, I don't see a way to solve the seesaw problem with a complicated and/or obtrusive linkage between them. Like one layer of the mechanism that keeps the top of this contraption parallel to the floor:
"Here's an idea to make the board better - lock and delete threads that turn into pissing matches."