A "cutter" in baseball is actually another name for a fastball combined with the old, near-defunct screwball pitch. If thrown by a right-handed pitcher, it will break in towards a right-hander.
Most guys who throw one do it one of two ways, either by adjusting the relative grip pressure of the two fingers, or rotating the wrist clockwise when they let go. The second method puts more movement on the pitch but also leads to more injuries. The current master of this pitch is Yankees' reliever Mariano Rivera.
Like in bowling, though, it's difficult to see how the pitch really moves because of camera angles.
Jess