That is definitely the right direction compared to before, so now I can try to get a few details/concepts from my perspective...I'm sure SW will spot a lot of specific body positioning things.
So in the first one leg pendulum video, start with the disc gripped how you want it. The purpose is to feel the mass of the object pulling your arm, or the other way of thinking about it...having your body pumping directly to the object. So you need that in-line and in control grip.
As for the bent arm thing, I understand the confusion and how it feels like it's not right to keep the arm straight. But even in that extreme hyzer angle when you go to throw, you can see your forearm lags back like 20 degrees, kind of like Feldberg when he throws. And your pump is completely off for when the power gets applied, which I will explain below. But my point is, if you start with a pretty long/straight arm and have the power/pump applied the right way, the forearm will LAG back and it will LOOK like the power pocket, rather than you trying to get to some elbow bent position halfway between reachback and hit. This is a big concept change for me as I was always focusing on the power pocket too.
In the one leg position, shift your head another 3-5" targetward so it is directly above your plant leg. When you turn back and forth slowly with the disc, it should make you feel like you want to bring your whole torso and your left leg along for the ride, turning at the same pace to stay in balance.
Your pump timing is off a bit, which is the main problem I see. You are crouching down to the bottom point of the swing, and extending up in time with the swing. What should actually be happening, is beginning to extend as the disc just starts to drop toward the ground, so you are already pumping it/extending through the bottom of the swing and accelerating it away from you.
If you watch this hammer swing video, try the elephant walk with a hammer. Watch how the outside or leading foot plants at the apex/transition of the hammer swing, and lands before the hammer comes down. This movement makes it so obvious how you need to time it once you've felt it, then when pumping between your feet in a standstill stance you can really feel how you have: top of swing transition->farther foot plant->foot weight starts to pull disc as it comes down->big acceleration through bottom of arc
https://youtu.be/Y-KVWfUkQ3s?t=280
It should be linked to 4:40