it always made sense to me, work done is work done irrespective of ending up with the books balanced over time, to do work or apply force takes energy.
Yes it was a angular momentum experiment that showed that with a energy input conservation of angular momentum can be shown.That coat hanger and battery experiment was to show conservation of angular momentum. It really confused a lot of guys. In the end, it showed the formula/law was correct, and a lot of energy was expended at our keyboards.
The same experiment can also be a good experiment for showing the pull of gravity (the hand pull on the string on the video) and the effects centrifugal force would have on orbiting mass, and how CF saps the pull energy and needs more input energy to repeat the experiment, perhaps take a look again and see how much like orbits the forces are acting on the low friction orbiting mass experiment, wherein the pull inward by hand is the force of gravity on the accelerating part of the orbit and the pull out is the CF deceleration part of the orbit see what happens when he stops applying the work done by gravity (his pull), and he lets go of the string, but the mass only flies out to the stops and gravity never stops doing its work (no stops just gravity's constant work) and never lets go, of which I am very happy it does not stop doing its work.
It makes no odds to me if gravity is called a conservative force, because it seem more than happy to do work and that is all I ask of it.
Edit, add words to put in order.