Idk for sure as you don't have a video. If you mean the walljump off the red, I just try to hit the right side. The jump in the end room I just jump while sliding to not lose momentum, and it's a bit random whether you get it with one jump.
There too you have to start holding control in the air to keep your momentum when you land. Then just jump and shoot (preferably behind you to get a push forward instead of upward) at the same time.
