Thanks to the creator of the TAS, there's a way to skip the autoscroller prior to the final boss. If you press A twice within 6 frames, you can clip into the ground or ceiling. This isn't humanly possible by spamming A, but it's easy with a simple pause buffer.

You just have to make sure you keep holding right as you do this trick, and only let go of it when the first mosquito is about to finish his first flurry of shots. It's not too difficult to time, but if you want to go for a safer strat, just never let go of right. It costs about 5 seconds but you should hit the "end level" trigger everytime.