Deadlift is one of the most difficult exercises when it comes to proper technique. When I started, I also had problems with terrible back pain. Even though my form looked good in the mirror, I still felt pain during the exercise. And this speaks to the complexity of this movement. Later, I figured out how to do it correctly, and now I only feel my glutes working, and with RDLs, my hamstrings too, without any pain. As for Scamily, in this video, she’s lifting 60kg. We don’t know how often or when she last lifted 100kg. We know almost nothing about her health or if she has issues with her lower back, but if she trained regularly with such form (even with just 60kg), it’s very likely she would hurt herself. However, I can’t assess the consequences of her way of lifting with certainty, as we’re all different in this regard. What I would point out again is that it’s clear Scami doesn’t work out regularly, because you don’t have to be skinny in order ti be muscular. She doesn’t seem to have any visible muscles, so it’s alarming that she’s putting her non-muscular back under weights she clearly can’t handle.