You got issues, but not bad. At first I was troubled by your rounded back, but the rounding is really thoracic, not lumbar. As far as I can tell, your lower back stays neutral through all the lifts. Do you have some thoracic kyphosis? It's hard to tell in the videos. Maybe you should work on doing some thoracic extensions (over a foam roller, med ball or PVC pipe), and some of the other things mentioned in the Neanderthal No More articles in T Nation.
When you set up, work on keeping your shoulder blades back and your chest high. Then let your body lean back a little, using the weight of the bar to keep from falling back, and "take the slack out of the bar." KPj described this well in his comment to Ken's DL form check.
Our greatest fear should not be of failure, but of succeeding at things in life that don't really matter.--Francis Chan