I'm amazed at the time and effort the maker of this 'ball track' (a free translation of the German word kugelbahn) must have put into designing, building and testing it. Just look at the number of soldered and/or brazed joints, and the angles he had to get right to keep the balls moving smoothly, and the intricate interweaving of opposing tracks! To see them better, I recommend watching it in full-screen mode.
It's pretty amazing, though. Full marks for dedication!