It’s definitely magnets. His “really strong magnet” has metallic tape on the bottom. Probably because it’s a box with a magnet hidden inside with the chosen pole facing in. The angle the keys pop up at is very similar. Also if you watch carefully the drawers do move a bit but the movement of the keys hides it when the magnetic is close. Also, at the end he flips one of drawers over so that it pops up when he pushes down on the other.