For the squats I basically paid the most attention to the warmup vid since 95 pounds should be enough to require proper form....
Judging from that I see nothing worth mentioning. You have your feet splayed a little on the far side and I'll bet you're doing that to make up for some lack of ham flexiblity.
Since you're squatting on carpet take off the flip flops, lol. That's a good way to trip and have a very bad accident. Just squat barefoot in that case. Lot's of people just use running shoes. I squat in chucks.
Anything you attribute to bad form on the 155 pound squats looks more to me like you working with weights that are pretty heavy for you. But I will watch them again a couple times to see if I can add anything....
Ham flexibility should be easy to address. First of all you could start out your workouts with some dynamic leg swings (both ways, front and back) and also some lunges where you focus on getting a stretch at the bottom but in a dynamic fashion. At the end of your workouts do a lower back stretch, and a ham and hip flexor stretch at least.
The easiest and most effective ham stretch to start out with, imo, is the basic lying towel stretch. You lie on the ground or a bench, raise one leg and hook a towel around the bottom of the foot and keep the other leg straight and on the ground (you probalby won't be able to keep the straight leg down at first because of hip flexor tightness). Then just use the towel to pull the raised leg toward you head, focussing on getting a good stretch in the hams. You do not need to have you leg completely straight. Keep a little bend in the knee. It will work better. But once you get to a point of good stretch you can try to straighten out the leg a little also if you want.
The basic raised leg stretch where you bend over it to stretch the ham is just as good as that but the problem is that the lower back needs to be kept completely set or you'll simply be stretching the lower back instead of the hams. But this can be difficult to do at first so the towel stretch elliminates that problem. This can also be done in a doorway.
One last thing. LOSE THE BELT. Not a good idea. You are sacrificing the development of core strength and it could set you up for imbalances...
You had asked before about that and I answered no. I don't think too many here would disagree with me on that and if they did I'd tear them apart in an debate
. But perhaps I should make that answer in big bold beautiful letters:
NO