The trick with his shot is how hard he hit it...the spin has a delayed effect due to how hard he hit it so what happens is that the cue ball follows the natural tangent of the shot, bounces off the rail THEN the spin finally takes effect and the ball spins back. no inside on this whatsoever..just smart play by knowing the angle. Watch how the dots spin, its why they are there so you can what kind of english is being used if any...
I do agree with you about how this shot is made, the force (plus hitting closer to center, rather than maximum draw) is what gets it to stun sideways first.
However to be fair, he definitely put inside on it. They show his warmup swings and you can also see his stick lined up to the right (his right) in the freeze frame.
http://www.youtube.com/watch?feature=player_detailpage&v=FTGMZVben94#t=2632s
I don't think the inside was 100% necessary, but it probably does explain why the ball went forward a hair (as JSP pointed out) before sucking backwards.