From what I saw just skimming it, you basically just sat down on your foot when changing levels, hypoextending the knee flat while all your weight and momentum was coming down.
Shooting is not the most 'natural' movement ever, so it takes a lot of practice to get your muscles comfortable moving your weight through the deep lunging motions without flopping. Id consider adding things like duckwalks and 'shadow shots' to your calisthenics to build up your ability to move while 'in the hole'.
And this is personal opinion, but I think its a good principle to make a conscious effort not to touch the ground with your knees while shooting like how you were doing. If you can do that while changing levels your technique will be a lot smoother and tighter (and avoid situations like what happened with Browne vs Barnett).