Can't see it, so just make sure your getting those knees pushed out to the side. Going too wide can also cause some issues that flexibility won't fix, so be sure your using that happy medium.
How to get loose... stretch everything! You seem pretty damn tight. I wish I had a name for everything I used, but I don't. Just google stretches for the glutes, grion, hamstrings, hip flexors/extensors, etc. If you can feel it pull, push at it a bit! Also go to MobilityWOD.com and do a search for "hips," "deep squat" and the likes. A great resource.
Aside from that stuff, take some weight off the bar and try hard to hit depth with decent technique. Build up from there. If you don't acclimate yourself to correct depth, your body is just going to cut that rep higher and higher as the weight moves up to avoid that weak area/sticking point/potential injury.