You gotta look at how the stone gets re-faced in the 2nd video to see that a curvature gets put on the stone face. The pivot for the refacing tool is angled downward a bit, which results in a curved finish on the stone.
I watched the video several times while he dressed the wheel. I couldn't tell if the pivot pin for the dressing tool was parallel too the floor or not. [Assuming that the wheel spindle and the lifter spindle are both parallel to the floor]. But since the close up pics of the lifters at the end of the video shows a 'crown' and not a point on the face, I assume you are correct, sir. ----- Pretty rough surface finish, though.
