Just so we're all clear on how it works..
-- Scartol
Black is not going to play as shown in the previous diagram. This diagram shows the best sequence for both players. (Scartol: Of course.. I just wanted to show the snapback machinations for newbies who have trouble seeing the snapping of the back -- like I used to.)
Suppose white does not know the snapback technique and directly captures the three black stones. Black will be better off by 2 points.
--unkx80