Hard to tell on vid.
- Firstly you seem a little unstable in your setup.
Experiment with foot placement/leg drive. Go through these steps:
A. Lay on the bench and grip the bar as hard as you can, Lock the elbows.
B. Much like you did in the vid, start squeezing your traps/back together and use your legs to drive your upper back/traps straight down into the bench cushion while keeping that good arch like you had. To do this, your legs will have to be out in FRONT of the bench, wider than shoulder width, you will have to experiment with angle/width to find what feels good. Since your elbows are locked out, your legs will force your upper back into the cushion when you push with them, make sence? In the vid it looks like you have good arch, but you never really drive yourself downward and "seat yourself" into the bench. Think of it as "floating" on the cushion versus "pushing" yourself into it with your legs. In the vid, it looks like part of the reason you are a little shaky is because you "float" until the bar is over your head.
When I get my setup, I like to:
Take one huge breath as I get under the bar
Once the bar is overhead I may wait an extra second or two to let the weight drive me deeper into the cushion. AND I keep my tension on my legs as I rep out.
Also, take bigger breaths, really try to fill yourself with air when you breathe, don't be afraid to bench with your mouth open. lol
Overall pretty good setup. Just really try to drive yourself into the bench with the legs, and keep your entire back tight/ breathing.
C. Your elbows flare, try to keep them tucked in at the bottom of the rep, to do this, as you lower the weight, keep the elbows inward as they fall against the lats. Breathing is going to help here too, take big breaths, try to really flare the lats at the bottom of the rep and let the lats catch the elbows so to speak.
Benching never felt great for me until I started doing a lot of barbell row. Lats started growing, all of a sudden, bench went up. So rows, T-bar and barbell help.
Good start though, also, Im no professional so just some friendly tips. Experience will help too, the more you lift the more natural it feels.
NOTE: I have lifted out of a rack like you have, with a deep groove for the bar to rest in, it makes it a bitch to pull a bar over yourself to bench with, because you have to lift the bar out of the rack instead of "drag" it over yourself, makes it really really hard to keep your traps together. So shop around if you ever buy new equip.
Overall, good job brah.