It’s much more reliable to use the ghost ball position of where the cue ball needs to hit the 8 ball and then measure that to the rail and then mirror that to the other side to find the contact point rather than using the edge of the 8 ball.
No clue what he's talking about but he made that shot with what he showed so I mean it's obviously something to do to learn a kick shot now for anyone except beginners you have a point
It may be incorrect, but at least his explanation was decent enough to make it recreatable/practiced. That crap J.billiards showed this without any explanation