How are you snapping the rotation of the new loop cuts you make? Specifically that loop cut along the top of the frame. It was at a slight angle but you snapped it into an upright 90 degree angle without distorting the mesh. Did you size it down as well? There is a video edit cut right there so I can't catch all of the key strokes. Time stamp is 4:30.
Hey Darrion! In retrospect it does look kinda cool how I've seemingly "rotated" the loop cut! To align the loop cut vertically on the top frame there, all I actually did was scale it to 0 on the x-axis. :) Because the top and bottom pair of vertices were on the same respective Y and Z axis, kind of gives the illusion that I rotated it!
Nothing too crazy elaborate, and I'm sure there are 100 better ways of doing it but I'm a simple man. :D