So I bought this game and unlocked Naija, even tho it's not really noticeable with the choppy framerate in the YT video.
Her ability is pretty hard to control, you can't "run" with her, but when you use the run button in the air, you change form until you let go, then you suddenly fly towards the direction you're facing in a steep curve upwards.
Then again, whole Super Meat Boy is pretty bugged on the abilities of the game.
Though then again again again, this should be still possible:
http://www.youtube.com/watch?v=YdcS83zLaLkAnd he makes it look easy!