It seems that the grooves pointing towards the centre of the platform make for an unnatural walking gait. At the start of a step, the foot will move inwards towards the line of travel. As the foot crosses the torso, it will move outwards again.
Whereas in a natural gait, each foot moves parallel to the line of travel.
See 2:10 of the video for how the shoes fit into the grooves using plunger pins, and how they move on the platform.
Note that at no point in the movement the torso moves up or down, so the forces on the joints/back are much lighter. So wouldn't that make the movement a light unnatural movement like swimming is? Do people get many knee injuries from swimming? (I had a knee injury that flared up when swimming, but I don't think it caused it)
Whereas in a natural gait, each foot moves parallel to the line of travel.
See 2:10 of the video for how the shoes fit into the grooves using plunger pins, and how they move on the platform.