You drive a car with both hands on the wheel, not a disc. On the hole, where the bearded guy had roll away and many attempts, he threw steep hyzers, that would hit the hill side in a 90 degree angle, if the disc held the line. Hitting the ground at 90 degrees is called a roller even on flat ground. To minimize rolling away you want to make the disc land at less than 90 degree angle at a minimal speed. That means throwing a disc, that is so understable, that it can move enough right to left at slow speeds without stalling and increasing hyzer so much, that the disc would gain the 90 degree landing angle. Grip seemed to be a problem on those throws. FLX Buzzz for a mid, Trak for a FW driverFLX Surge SS and some of the tackier Gateway putters for grip and breathing on your fingers just before the throw. Maybe hand warmers and there are reusable kinds as well. Using the left hand to twist the flight plate against the thumb should help too. The hip was twisted to the left and it is ok for so steep drives as the last one, but usually you'd want to be more upright at the hips. The putt on that hole had the wrist down, so the front of the disc was lower than the back=diving short of the target. A flat release would probably have gone in.
The bearded guy is making a swimming jump start with the left leg. You lose power and balance=accuracy in pushing up and forward with the left leg. The direction of the left leg push should be forward.
Weight back is an issue and pushing forward should help.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.