Missing variant
They should have added a case where the electromagnet was turned off with a delay after the box was inverted.
Even so it proves little, very few humans that can ride a bike understand the physics, I doubt many are even aware that they use countersteer.
Alternate experiment.
A treat/toy is is dropped in sight of the cat. If the cat gets the timing wrong the treat/toy drops through a hole into a catch box.
A treat/toy is is dropped in sight of the cat, it then disappears behind an opaque barrier before re-appearing in front of the cat. If the cat gets the timing wrong the treat/toy drops through a hole into a catch box.
A treat/toy is is dropped in sight of the cat, it then disappears behind an opaque barrier behind which is a device to delay re-appearence in front of the cat. If the cat gets the timing wrong the treat/toy drops through a hole into a catch box.
A treat/toy is is dropped in sight of the cat, it then disappears behind an opaque barrier behind which is a device to catch the original treat/toy but release another that will appear in front of the cat at the right time, but the wrong speed. If the cat gets the timing wrong the treat/toy drops through a hole into a catch box.
If cats understand physics the last two will really mess with their heads.