It looks like pure magic in the end even though you see how it works at first.
Despite seeing it work at first I didn't even register my amazement until I saw it on the horse model. I was just thinking, oh a cool knife sharpener..?
The video is itself a demonstration of how magicians use indirection to distract the audience from what matters, to something that is beside the main point. When we are first shown the translucent model, it is not clear that the head end is only supported by the cams. As the demonstrator pushes the blade down the slot, he talks continuously about how the movement of the cams causes the ears to wiggle. By the time the blade has passed through the device, we have all the information needed to conclude that the head is not connected to the body by a simple rigid support, but I, for one, did not notice this - I was still waiting for whatever is special about this mechanism to be revealed.