Show off throwing with both arms and sidearm
Throwing from sand may cause slips and lead to false conclusions about timing and what it takes to keep the rear leg on the ground, the length of the pause and how to achieve it, getting the elbow forward and so on. In order to polish elbow forward and test a longer pause i recommend to throw from a grippy surface. You definitely need to test heel pivot vs ball of the foot pivot. But before that you need to improve the ball of the foot pivot into what it can be meaning the heel needs to be higher so that less sole touches the ground. So that the foot pivot happens with less friction that twists your leg enough to endanger your long term health. The pivot gets even more stressful to the leg when you add power by moving faster possibly taking run up steps and taking a follow through step with the rear leg after the disc has left.
You are not engaging the hips and the shoulders as much as possible but fh is especially lacking.
You are bracing obviously but the knee collapses forward and then it straightens it by pushing you backward. That is not so helpful to shifting the weight forward. You could gain a hair more power if you did not tilt forward from the hips. But it is a very useful flight manipulation when throwing under obstacles or in the winds and if you cannot yet get enough nose down on the disc. So it is definitely a good skill to have but for all out distance it is better to achieve an upright posture at the hips in the hit.
You can optimize pull height etc. but really what you need now is to add more speed to your movements while keeping the great looseness and ease of the last video in the fh arm swing beginning getting a good late acceleration. It is good. So more speed and body into it and you're gonna see improvements in distance and controllable consistent distance as long as you don't run pell mell and suffer too much in form. That is nigh impossible to feel and video helps to keep it real as you add more speed and power.
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.