I'll jump in, though I agree with what's been said, more to emphasize a couple of things. Depth is a good thing up to the point (or should I say "down" to the point) that you can't maintain a neutral lumbar spine. If you have to let your low back round in order to go deeper, you're as deep as you should go. Keep that low back tight as you are keeping your abs tight, and you will feel where the bottom should be.
You need to treat the bar with more respect. By that I mean, act as though you have a new PR on the bar, and one misstep will crush you and ruin you for life. Well, maybe not that bad. You can get away with looseness with 135, but you won't when you're squatting bigger weights. When you unrack the bar, you are leaning forward, and lifting it off the hooks be "gm-ing". If you saw someone do that on a rep in a form check, you'd pick it up right away. Set up under the bar in the same relation to the bar as if you were locking out a rep. Picture a line on the floor that's directly under the bar, and center your feet over it. Then get tight and squat the bar straight UP off the hooks. Then and only then step back. I really agree with what Nygmen said about fidgeting and looking around. After you squat the bar off the hooks, take a step with one foot and then the other, and stay there. I know that in the form check you were posing for the camera, but on a real set you won't have to worry about that--just step, step and you are in position. And keep your head straight forward and your neck neutral, not looking up and down. Maybe allow your head to go up a little as you drop into the squat, but not straining back like some do. Keep the muscles of your neck tight, but don't bend it back, nor let it fall forward in relation to your body. Then when the set is done, keep good tightness and walk it in--step, step and you should be there, both feet under the bar, not one ahead of the other. My steps in tend to be shorter than my steps out, so sometimes I'm in danger of missing the hooks, but I try to wait until I hear and feel the bar hit the uprights on each side (not looking back and forth) until I drop down, staying tight like I'm doing another rep.
I ramble a bit, but you're doing well over-all.
Our greatest fear should not be of failure, but of succeeding at things in life that don't really matter.--Francis Chan