Your DL is not great.
First serious issue, you appear to be bending your elbows and curling the weight at the top of the pull. You definitely don't want to do that. You want to lock your arms long and tight.
There are several other issues but you can address all them by watching this:
https://www.youtube.com/watch?v=ToXDFLXL1uo
Squats are not bad at all. I know you are struggling with the concept of your lower back failing. That is to be expected.
Unless you grew up on a farm or working construction, almost everyone in first world circumstance is weak. And, when it comes to starting out on the backsquat, almost everyone's back will fail before their legs fail.
For a cue, try "chest to wall". Meaning that you are pushing your chest flat against an imaginary wall and squatting down and up with your chest glued to the wall.
More importantly, understand that you have to get super tight and then stay super tight. Your focus should be on your back being locked in position through the entire range of motion. And, yeah...it's hard to do.
When you take the weight on your back, your brain's sympathetic response is like, "wtf, that **** needs to get off my back". You have to override that. It takes direct mental energy and effort to do that.
Don't overstress. Just keep working as hard as you can on every rep to keep the focus on your back. Your legs will do their job on their own.