When you reach the 3 little fast-moving lifts, the middle of the 3 sections in the rear room is a secret door.

Jump over the ledge next to the waterfall. Underneath the ledge is a secret room.

Rocketjump from the ledge to the top of the waterfall. Here is the entrance to the very short secret level #2: 'Sudden Death'. When you arrive there, you have ONE try....

To the right is the exit from this level. In the middle, a giveaway button is hidden. It opens a door to the left.