The walkthrough isn't actually that great for level 22. It's easier to beat it if you use 'Goomba' to jump over the green button and the fireball, then hit the red switch and getting to the little nook to the left of the cannons, then hitting the green button.
Up until now, I thought it was fine to scare the living daylights out of people on the ground floor until someone on the ground floor decided to run upstairs just to jump out of the window. Anyways, one of the best games I've played in a while, 5/5.