"Super-magnet ramp" is world's best visual illusion Answered
In a packed concert hall, Kokichi Sugihara wields a pickaxe and mimes a blow to the stage. "I am a miner, and I have a secret," Sugihara says, adjusting his hard hat and headlamp. "I have discovered a new super-magnet."
A screen behind Sugihara begins playing a video. A cardboard structure appears, consisting of four ramps ascending to a raised platform. A hand places a wooden ball at the base of a ramp, and it rolls uphill, before stopping on the 'super-magnetized' platform. As the same trick is repeated for the other three ramps, the crowd lets out an "ooh".
Thanks to Kiteman, here's the author's own Web site: http://home.mims.meiji.ac.jp/~sugihara/hobby/hobbye.html
Image and video from Koichi Sugihara, Meiji University.