So judging by his videos, that would mean...
Everywhere?
Just take the wind out of chapter 1, the tetris blocks out of chapter 2, the walls and enemies Out of Pipe Dreams, the water and broken booster in the water room, the bosses out of the boss fights, the spikes and enemies out of STARS, the rails out of the railway, the maze out of the matrix, Interrobang out of the interrobang fight and BAM! Easy mode