Form Check for Deadlift and Squat, Newer Lifter

[cjr243]

Looking for feedback on ways to improve form. Have been lifting about 2 months on stronglifts 5x5. Have had no lifting buddies/feedback aside from reading online and unsure of what I'm doing well and/or doing poorly.

Fifth set of 245lbs, last rep was getting really shaky.
youtube.com/watch?v=5LWm5Q-yrb4


Deadlift 225, and 315. Lots of dead time you can skip in the video sorry!
Worried about keeping back tighter all through especially at higher weights. Grip was struggling (had no chalk at the time)
youtube.com/watch?v=9PgvLqwoq7w

Thanks.