What program are you doing ? (if it's SS, i'm surprised to see multiple worksets)
These look fairly alright i think... certainly no crazy back bending action.
However, when you're setting up it looks like you're raising your head more than squeezing you chest up. So keep your head more neutral and really force your chest up more. (and "up" in this case is really forward since you're bent over... )
Also, you can take another second between reps to set your back. It looks like the last 3 reps are a bit less set than the first 2.
Finally, fight to keep your back straight on the way down too. You're putting the weight down at a good speed, but don't do it by relaxing the back.