Hey guys. The most glaring thing to me is that I round my back but any critiques or suggestions will be appreciated. The first video is of 365 and the second is 405.
The rounding issue is partly caused by your center of gravity shifting forward as you initiate the pull. Your ass is coming up too soon, or it's starting too low. It's hard to say for sure without video of different examples to compare to.
Try to sit back more. taking those silly looking shoes off may help.
^what Bonez said, your upper back needs to be moving at the same time. push through with the hips
I believe you "think" incorrectly when lifting.
When deadlifting it's important not to "pull" but rather to "push". Try to push your feet into the floor as if you wanted to break it this should solve the upper back and ass problem.
The comments here so far have been spot on. It's hard to tell from the vid but is the bar in contact with your legs all the way up? Definitely need to sit back more.
One good coaching cue that I find helpful is once you've sat back and you have that tightness in your hammies, use your hamstrings to dig your heels into the floor. This will bring your hips through as caveman101 said.
Also maybe consider using a belt? Not essential, but once you've learned to use it it may help you train out a few of the bad habits that you've picked up. Pretty solid pull overall, but definitely some work ahead in order to take the training wheels off and really start to fly.