I understand what you mean and that is also how you explain it in text in Fundamentals. However, his disc and arm would be to the left of the yellow vertical line in the picture referring to that topic which confused me a bit.
Anyway, any comments about the stride angle?
Yes, totally an option. To intregrate the two think of how upper and lower body related to each other to maintain balance.
I think most of the lines in that Inside Swing section are taking the literal wall from SW's Inside Swing concept. SW usually emphasizes the straighter reachback in drills so the abstract wall & yellow lines are a little easier to grasp in that case.
But if you get extreme out-in-out like Paul the first "out" will appear through the wall at that angle like you are saying, Hampejo.
From there I would be watching his backswing in relation to his chest and where the shoulder and elbow are leading relative to the plant leg there. In "Inside Swing," the shoulder should stay relatively along the wall as it clears over the front knee. The elbow should come back through the wall as he enters the pocket as does a straighter or more behind the body backswing. The net result is an action that brings it all inside his posture to commit the shot.
I usually think of the stride angle as related to that action because if he doesn't do both that stride pattern and the wide rail together, I don't know that he can land in balance (you need the lower body to be countering the action of the upper body in general to do so).
Or that has been how I have tended to think about it.
Couple interesting things to point out about this in general and specific to your clip above.
Shoulder supposedly comes along the wall in Inside Swing. Each line is "the wall" corrected for his balance axis. Interestingly in this case in the wide rail Hampejo shared above it looks like his shoulder comes "off the wall" earlier than most of his shots I've seen (marked yellow in center). Not sure if that's intentional of course. The pink shirt angle is just chosen for a different view; you can test the idea in other videos.
Elbow goes through the wall entering the pocket in each case.
Left image is straighter reachback.
Right images are wider rail, the one with pink shirt was from a little while back.