ah thanks, I can kinda picture that..but how/why does the inside spin eventually become outside?
As bbb stated, the cb loses the inside spin when it strikes the end cushion, and then it rolls off of that cushion (which produces a little left/running spin), then it just rolls into the side cushion and bounces out.
You really have to stroke a shot to keep inside spin on the ball after it strikes a cushion, and the angle that it hits cushion can't be too steep or the ball will lose its spin and come out rolling.