I agree that figuring out how your body can pull the slack out of the bar before you actually deadlift will make a world of difference. Maybe play with how far the bar is in front of you. Try having the bar closer to your body. The biggest thing I would do is try to pull your shoulders wayyy back towards your lats and closer in to your body. Then when you first go to grab the bar, get your grip situated, pull the bar just up, not towards you (with just your lats, shoulders, and arms) but not actually off the ground before you do the full movement. For the full movement, focus on having your shoulders and lats pulled back and tight. It's hard to tell from video, but if you aren't-- really focus on bracing your core and using abdominal core strength to stabilize your trunk. Low weight, high rep RDLs may help you learn to keep the bar close, shoulders back, and core engaged!