Ugly shift during squats

[ging]

Hi coaches, I have a bit of a problem with my squats, my ass seems to shift during them, I've tried everything to fix that stuff but nothing seems to work, here's two videos showing that, sorry for the shitty angle, the gym doesn't allow pictures or videos so I had to be careful and it's pretty small too, I'll probably be switching gyms soon and posting better form checks
Here's the video: https://www.youtube.com/watch?v=LdwG...ature=youtu.be sorry about the bodybuilder getting in the way, nothing I could do about that

[Tom Campitelli]

I need a better video. We really couldn't see your reps. Need to see more to have an idea.