Yeah, get some lifters.
We ask for a work set or challenging set of five reps because at that weight it will reveal things that lighter weights may not.
You're not stopping at the top and bracing for each rep. You're also too vertical while trying to send your butt back so your back is going into slight over extension to neutral when you hit the bottom from what I can tell. Video's a bit blurry to be sure.
Get your chest up at the top and our elbows down. Breath and brace before each rep.