Deadlift form check

[Armin00]

Ok so after my deadlifts i left with a sore back...again. I gettin pissed off to be honest cause im getting stuck in around the same weight because once I do some decent weight deadlifts im left with a sore back. I cant seem to get in the right position in the first place. I just cant get to straighten my back fully. I'll post 2 videos of me. 1st 132lb and 2nd 242lb. I didnt want to go as heavy as i can cause i didnt want to leave with the sore back again.Im 6ft2 if it helps.
Thanks Jsutt

[Jsutt]

Your back is sore because your lower back is in flexion. Start with your hips higher, don't bounce around so much, set your back as hard as you can and hold it straight through the lift. Do you notice that your hips are moving a lot before the weight breaks from the ground? They shouldn't do that.

The back is better in the warmup set but your hips are still too low. Also is that all the lifts you did for that workout? If so, more warmup sets might help with the pain.