Today's revelation: Dice Stacking. According to Wikipedia:

Dice stacking is a performance art, akin to juggling or sleight-of-hand, in which the performer scoops dice off of a flat surface with a dice cup and then sets the cup down to build a vertical column of dice. Various dice arrangements, colors of dice and scooping patterns allow for many degrees of complexity and difficulty.

Okay, what? Here's a video from Thomas Fischbach demonstrating the art:

Am I correct in understanding that these are just regular cups (no internal structure holding the dice), and he's using centrifugal force (and his index finger, sticking in the top of the cups) to do this? Any dice stacking experts in our readership who'd like to explain what's going on here, please do!