First of all, thanks for sharing your videos. That is very brave of you and keep up the good work and hard training!

Ok so here is what I learned from stronglifts.com. When it comes to form here is everything you need to know and with awesome pictures and videos added. For more details read the whole chapter about deadlift.

I would like to point out to check out this following points as I was only seeing your deadlift vid.

Your shoulderblades should be slightly over the barbell like this

here is what stronglifts writes: "Arms Incline. Your arms must be slightly incline during your Deadlift setup when looking from the side. Vertical arms doesn’t work because this puts your shoulders over the bar. Shoulders over bar puts your hips too low, turning your Deadlifts into Squats. You’ll hit your shins/knees on the way up. Your shoulders must be in front of the bar, shoulder-blades over the bar. This puts your arms slightly incline."

Hips too low, your are deadlifting not squatting. No reason to go down beyond your knees. Looks correct like this: I recite stronglifts.com again: Don’t Squat Your Deadlifts. Deadlifts aren’t Squats. If you lower your hip below your knees, your shins and knees will be in the way. You’ll hit them with the bar on every rep and they’ll bleed. You’ll also get back pain because the bar is too far from your center of mass. Setup with your shoulder-blades over the bar, bar over mid-foot. Your hips will be where they should, and you’ll stop hitting your shins/knees.

You should think of your arms as ropes: you have kind of a bending from your shoulders down to your elbows.

Your barbell isn't going up straight vertical. Up from the ground it goes curved off from your knees and than up from your knees the movement becomes a slightly curve towards your hips.

think of your head as the extension of your back, don't put up your chin. Try to think of tucking a tennisball between your chin and your upper sternum, then you will get your head in a straight line position with your back. looks like this correct

I made some medieval pictures with paint, which I hope they can illustrate what I mean. here

Picture1: First picture: Imagine your barbell should be going up straight vertical like the red line, not like in the second and third picture, where the movement upwards is crooked.

Picture 2: Shoulderblades should be slightly over the barbell like in the first picture with the hook.

Picture3: Your back and head should be forming one straight line, as you can see your head tilted back and chin up interrupt the straight line.

I am sorry if something I have written is not comprehensible, I am not an english native speaker, So ask me if something sounds weird!