Notice that he is using a 3/8-1/2" wide strap of leather, and not a rope to transfer energy to his spindle from his pole. And, Also notice that he is wrapping the strap around the spindle 2 times , rather than just one.
Finally, notice the diameter of the spindle. This is how you get both leverage and powder , because the leather strap has a wide surface to contact, while spinning the work on a smaller " point ". This is the same as using gears to increase the power of a machine.
Good film if dark in parts. He's obviously made hundreds of similar bowls, to know what angles and shapes to use inside and out so he can free-hand cut the inside without worrying about cutting through the wall of the bowl. You don't see that bent cut off chisel very often. I suspect that he may have had that made, or bent the shank of a straight chisel to curve it for his purposes.
