D2K.
Jumpman, on the foundry stage, does a straight jump, stands there for a few seconds, walks past the ladder, jumps over two of the fire pits, then falls into the third.
Every single time, with no variation, and there are no alternate sequences showing one of the other new stages or classic stages. Just that one. Over and over and over.
I've tried to understand what Jeff K. was thinking, and the only conclusion I can come to is that it's a joke of some sort.