Beginner squat formcheck

[a2242364]

VID_20170404_094717~3[1] - Streamable - some weeks ago

VID_20170418_144703[1] - Streamable - today


I had a lot of lower back pain on the squats for the first video, so I tried to do a more classic rippetoe style squat, but I get a bit of buttwink. Now, I'm not sure if it's actual lumbar flexion or if it's just going from extension to neutral. Either way, is this fine or do I need to eliminate it? The pain was significantly less, but I also did 5 less reps than last time.
Advice appreciated.

[andrew9977]

In first video I think you are looking too much downwards by me looking at your hat. Try looking a little bit more forward like past the bottom of the rack . This might help you set your back better. Second video, it looks like the bar might be moving around on your back which could be throwing you off. I could only guess this because the clamps change their direction. Try a 45 degree angle video from behind you too it helps.