@Feeder
I have done brick breaking before. It is possible that the Shaolin video is completely legit, but it might be deceptive, even if it was not meant to be.
Paving bricks (which is what that looked like) take around 400 psi (according to the instructor) dead center to fracture. This doubled for each 0.5 inches you are away from the center. It is totally doable, even for a normal person, but the real issue in the video is that the brick is only supported on one side. The increases the need for high impulse, otherwise the brick will just flip off the stand. It might be possible, but I suspect that the bricks are not typical pavers. Similar to how some groups use thin wooden board for demos so that it looks more difficult than it is.
As for Kingriver, his fingers would be a pulp. You strike unyielding objects with the meaty part of you palm, so you don't break every finger.