Just one thing about your last drill there & I've seen this in a couple people (and had trouble too) - it kinda looks like you're really emphasizing the crush as an action of the leg extending maybe at the knee into the ground rather than dropping onto it and resisting the ground. That's what SW is doing here. Literally hopping on one leg like this was very helpful for me:
And Gibson is doing it here in his "shift from behind".
You sometimes see a little bit of plant leg extension at the knee before impact like you might notice in Gibson there, but I think that's mostly about just helping soften the impact/transition the ground reaction force faster. The leg should just swing in and catch you naturally.
So, you really want to get the drop and feel the action of your leg preventing you from collapsing kind of driving the rear hip open - like SW is saying it's smooth but powerful. The better you land on it in a way that clears that front hip smoothly, the happier your joints will be. This didn't happen naturally for me moving in the BH direction so I had to exaggerate it a bit/focus on resisting the ground harder in One Leg Drill even after hopping at first.
Orthotics/flat feet: I'm flat-footed but perhaps not quite suction-cupping like SW. I had a spiral fracture in my left leg when I was young leaving it to develop a little shorter than my right leg. I'm flat-footed and wear a taller orthotic on the left foot than the right - that also initially started after some knee issues. My ankles also used to be pretty weak and I would roll them frequently. I've had the most success with Merrells that fit snug but not too tight and are very stable when moving laterally. Seabas kick the can and conscious attention to walking with more plantar flexion has helped with some of the foot stuff since I've probably been moving flat-footed most of my life.