Hey DannyP
Camera angles / clips;
2nd video with 300lbs captures a better camera angle from which to observe a form check out of the 2 video links you sent.
Mirror;
STOP LOOKING AT IT! Mirrors are very distracting and never help in self correcting your form ever! use a rack where there is no mirror in front of the squat rack or put a huge mat up in front of it so you stop looking at it. or stick up a piece of paper or something as a reminder NOT to look at it.
Elbows;
your being TOO aggressive shoving your elbows up when this is not actually NOT helping your flexed wrists in the low bar position. (Think of rotating your palm over the bar more still keep fingers wrapped around the barbell)
Chin;
in the bottom of the squat your chin is up. Try squeezing a tennis ball under your chin with empty bar and light warm up sets to correct this issue. Correct chin angle can help aid/cure a lot of issues with your current squat too, especially your lack of hip drive and knees out will improve with a correct chin angle.
Knees;
don't let your knees collapse as you come out of the squat. It is especially happening on your right knee. a great tool i use to cure this is incoporating the hip circle in your empty bar and light warm up sets, link here;
Hip Circle
Food;
You straight up need to add more food into your current daily intake judging from your physique. If you have a problem increasing solid food intake then try GOMAD, a gallon of milk a day.