That looks like a good start to me cuz even without weight my back keeps titling forward at the bottom of the squat and i feel it in my back when I try straighten in it up
Watch Overtimeathletes channel he has a bunch of videos on Vertical Jump training and he has a crazy vertical himself. He trains a bunch of professional and collegiate level athletes.
Barbell back squat one rep max has actually shown a very high correlation with your vertical. After starting strength training for around a year, a friend of mine got up to a 350 lb squat and was able to dunk a basketball at just 5'8" height
How to overhead squat=do an overhead squat lol. I think you forget most people can hardly get anywhere near this in the beginning, even with plates under heels
He broke it down pretty simply. If you can't do the extended arm goblet squats, then just do regular ones, or do plain old bodyweight squats until you have the strength & balance to move forward. I mean in all fairness if you're a true gym beginner you shouldn't be attempting an overhead squat anyways, not until you can do the simpler exercises.
I don't think the video was made for a complete newbie but for anyone looking to learn how to practice this form. If you tried it and found that you're not ready, that's ok. You'll get there if you keep building on the basics.
