Those looked like some crooked leg Romanian deadlifts. If you want it to be a DEAD lift, the weight must come to a stop on the ground between each rep, so that you lift it from a DEAD stop. You’re gonna fuck your back up big time if you try to descend with the weight slowly enough to keep it under control for the next rep.
Set up with the weight on the ground, not on the rack, grab the bar and lift it. Keep your back straight, chest out, head up, and the bar up against your shins. At the top of the lift, squeeze the glutes together and then drop the weight back down. Don’t actually let go, just descend quickly and let the weight stop, readjust your grip if you have to, and do it again. Fuck that was the worst attempt at a deadlift I’ve ever seen.