Your squats look fine, although the weight is obviously too light to highlight latent issues. You should probably get more air at the top, get much tighter (i.e. brace very hard) and pull yourself down into the hole rather than dropping into it. Like lift206 said, a heavier set will show more flaws.
Looking at your deadlift, I would suspect with heavier weights in the squat your trunk would pitch forward quite significantly and your lower back may well round. While keeping your chest up and pulling your elbows forward throughout the movement will mitigate that to some extent, if your lower back simply isn’t strong enough to keep your trunk upright you will still come forward.
With your deadlift, lift206 is dead on again talking about leading with a high chest. Just stand up with a high chest. Imagine an orange or something in your armpits and try to crush it while bracing your midsection as hard as possible. One other thing I did notice is that you seem to accelerate more pushing your hips through rather than off the ground which is kind of the opposite to what you expect from a conventional pull.
I would hazard a guess that’s because your hams/glutes are stronger than your back so they’re better able to move the weight fast - so you are relatively slow off the floor because your back can’t move the weight so fast. Also, I wouldn’t worry about lowering the bar so slowly. As long as you don’t let go of it, just let it come down and follow it.
I would recommend supplementing your training with barbell rows, pull ups and good mornings as well as squats paused in the hole. All of those will really help your back get much stronger and should enable you to squat and deadlift larger loads.