Your basically doing a romanian deadlift off the ground. Your back is close to parallel to the ground when the bar starts moving.
Your back might be a little rounded, but it's not too bad at all. If you ever have any sort of unusual back sensations that might indicate impending injury, you might want to work on that but otherwise I personally wouldn't.
So here's the good part. You've got an okay hip hinge. I don't think you're setting yourself for injury.
The bad part is that you're not using your quads at all as you alluded to already which means your not lifting as much as you could.
Remember that the bar won't come off the ground until your armpits are over the bar. That's where the spine of the scapulae is. It looks like your trying to start the lift with your armpits behind the bar then as you try to lift it up you go to the armpits over the bar because of physics which lifts your hips up and moves your knees back before the bar starts moving.
The shoulders behind the bar cue is for people who start too far over the bar. That doesn't seem to be you so I might drop that cue. Keep in mind it's kinda hard to tell for me since the vid is on its side.
Now from that position that I mentioned you pull your hips down and back.
So I would drop the weight to practice this new form while working on quad strength/muscle with narrow stance back/front squats, leg presses, leg ext, lunges, etc.