Every player, pro or not, has a weight shift where the majority of their weight shifts from rear leg into the front leg. There's a specific moment in that shift where the pressure maxes downward into the ground. It is directly associated with the brace moment. At that moment I am looking at how much twist or load there is on the hips in relation to the shoulder angle and where the disc is in its journey towards release.
One of the problems I see in these forums with freezing video images is that one can take one player and compare him with another when certain events appear to be happening but in reality aren't frozen at the right time as per each person's own mechanics, timing, and style. Some players will reach back sooner, some later. Some will shift quicker, some later. Some will have a quicker pull into the power pocket, some more delayed. What I fail to see most of the time is freezing the frame at the crucial events. For example- just because a player may have his front foot in full contact with the ground doesn't mean anything for determining the moment of weight shift and max brace pressure. Then it compounds when you factor in that each player has slightly different timing and hip and torso rotation angles.
The bottom line is, it's really hard, if not impossible to just freeze a frame and then try to compare him with someone else who may be, and probably is, in a different point in the delivery. Im afraid of the cookie cutter approach. Just because one certain pro or amateur steps a certain way doesn't mean everyone should do the same.
The actual moments of actual weight shift and brace max pressure and their relation to where the disc is has more to identifying problems or strong points than almost anything else. Weight shift is a transition. That happens just prior to max weight or brace pressure. I can always tell, right before I release the disc, if the throw will be powerful or weak. Thats because I am feeling the torque in my torso and shoulders at the moments right before and around the max brace pressure moment.
I do this little drill where I will just go halfway and stop around the point where I bring the disc into my abdomen/chest area. I am specifically looking for and feeling the torque and its relation to the brace moment. That monent should feel like a great buildup of pressure and torque. That's because after the disc is into the power pocket, the kinetic energy is already being released. Many players speak of a steady acceleration into release. This is somewhat true. It's true for the end appendage of the arm. But at release, the max torque of the hips and torso is already decelerating, they are already past their maximum acceleration and power moments. It's just like a whip. By the time the end of the crack of a bull whip happens, the hand has already slowed down or stopped.