SIAP...not sure if the camera is adding to the movement...otherwise, that is a sick pitch. Even fools the catcher.
The changing of the angle adds to the movement slightly... but having caught and tried to hit a few knuckle-balls in my time, they are effing insane when thrown correctly. The problem, there are only a handful of people in the world who can throw them consistently. If you don't throw it correctly, it is basically a batting practice pitch. RA Dickey is a phenom.