Hand-cranked shell game

[mklotz]

You can see the flags pressing on a small, movable wooden bar that's under the table.

I based my analysis on the fact that the spherical ball does not roll when it's revealed. Given the vibration induced by the hand-cranked motion, some force must be restraining it; the logical candidate is magnetism.

The gray skirt on the table is not just decorative; it's there to hide your view of what's going on underneath.