See the part I put in red. If you are hitting the ob at an angle, I agree. However, if you are hitting the ob full on, and the cb passes through where the ob was, it is an obvious foul. On a full hit, the cb ALWAYS comes to a stop. Draw or follow then determines if it comes back or goes forward. The only way it can go forward on a full hit and then draw back is if you double hit the cb. Plain and simple way to tell if it was a foul or not.
Did you watch all the video's? It is very possible to hit the OB full on and the CB can pass through and then draw back without it being a double hit. Not with a Level Cue or Even a Slightly Elevated cue though.