Whoa, video!
I haven't read through the whe thread, just skimmed to see if you'd posted any others.
Couple things...
1. Couldn't tell if you were wearing a belt or not. Couldn't full screen because I've got another playing outside the browser.
But!
If you're working with a belt, train with it on from the first warm-up to the final pull. I've had a lot of guys warm up and throw a belt on for their working sets.
You're effectively starting cold though.
Setting up with a belt is inherently different than setting up without. Absolutely nobody can tell me that it doesn't change their form / pull to some degree.
As far as that set up goes - plant one foot, then the other. Grab the bar, bring your hips up to get a belly full of air. After that, instead of just sitting down, let yourself almost fall back.
It'll help you pull the slack out of the bar and allow for a more efficient transfer of kinetic energy. Play around with your hip position to find what's right for you. But as a general rule, the crook of your elbows will rest against your knees. Unless you've got super weird proportions that'll usually put your hips in about the best starting position.
Work on that and take another video! It'll improve both your form and pull, and pave the way for more in depth critiques.
2. You're really shaking and grinding to lock out. That's a huge red flag that tells me you're glutes aren't doing what they're supposed to.
You need to wake them up before deadlifting and squatting. Get your hips moving in a way that mimics your main move - kettlebell Swings and box jumps are great.
Do 10-12 rep sets as you're warming up and drop down to 4-6 rep sets as you reach your working weight. This in and of itself will make a huge difference.
Also focus on movements that target, not necessarily the back, but the posterior chain. Cable pull-throughs are way underrated, glute ham raises, and either good mornings or Romanians (whichever you feel more through your glutes / hams, I'm a GM guy).
A fan-fucking-tastic assistance movement?
Throw a band around a rack and put it around your hips. Step out and do stuff legged deadlifts. It'll force you to focus on the hip drive, because you'll have the band actively pulling you back into a hinged position. Light weight...this one isnt about the bar.
Anyway, I'm tired and half drunk. So if I haven't explained anything well here, that's why. Feel free to ask for clarification if desired.
Then go do this shit and pull moar.
