Re: Help with Overhead Squat
Honestly, your positioning looks pretty good, and it looks like you've got the requisite shoulder and hip mobility. Ankles look like they might be hitting end range towards the end of the lift and you're shifting weight a bit forward to compensate--kinda hard to tell if you're getting any inward collapse of the ankle from the angle the video is shot at, but focusing on ankle mobility and stability will likely help your bottom position.
As someone else mentioned, you seem to be biasing the weight of the barbell behind your center of gravity. That almost looks like something that's a response to a coaching cue like "keep the weight back" (a pretty common coaching cue in the OHS), but you're maintaining a very upright torso, so that cue is not really helpful.
Biggest thing that stands out to me is that you seem to be lacking some stability and general comfort/confidence in the positions of the OHS. As others mentioned, just spending time in these positions is going to be a big help. Do lots of pause reps and/or just hang out in the bottom of an OHS. It also looks like your armpits are facing out--ideally you want armpits forward (more stable position). I'd recommend creating some torque and stability by putting external rotation force on the bar--this'll help with the loosey-goosey stuff and help keep your shoulders in a good position.
Lastly, don't be afraid to (slowly) add some weight. Often we have deficiencies/inefficiencies that can hide when the weights are light, but start to make themselves known as some weight is added. I'd be willing to bet that the barbell behind your center of gravity business will make overhead squatting with any moderate weight impossible and will fix itself right quick as you start slowly increasing the weights.