Ok i think i get the logic now. Makes more sense. Here is some psuedo code to work with.
The earlier video you had was better then this one. But this one shows what your doing more and really explains a possible solution to your problem. Your using the x, y position of the charector and how it rotates to determine how to move the points of the trees and the enviroment around you.
When doing this you have to keep in mind of how its moving and where its moving, if you move horizontally the enviroments pixels should only adjust to the horizontal. If you move vertically your pixels should adjust to the vertical.
you know how to do that so far, Keep that code it functions and works.
Now you need an exection to the rule. You need code that alters the x and y dots of your pixels according to the rotaion of your viewer. This should be activated and executed when and only when you need to move in diagnol directions.
you can use a boolean to determine when that happens if you want.
SO basically. Take his code. Take your code. Mesh them together.
Lets see what happens after that.