Joe,
You RDL pattern is actually pretty poor, so much so that you aren't really even hip hinging. This is due to the way you move around in day to day life. When reaching down to pick something up, you are primarily loading your lower back and not utilising your hips and hamstrings. The same is true of your hip hinge. You're just trying to reach down with a flat back, which is not what a hip hinge is about.
A hip hinge is about hinging at the hip (duh?), while maintaining a fixed relationship between your hips and torso with a braced core and neutral spine, and loading the hamstrings and glutes. Your shoulders should stay roughly over your feet, meaning the most obvious movement should be your hips reaching backwards until you reach your hamstring range. During this movement, your knees should be "soft", meaning that they shouldn't be locked but you shouldn't try to actively bend them. Your knees should not travel forwards at all.
Fix that stuff and you'll be well on your way. This should translate into your deadlift and things should start making more sense.
However, I will repeat a point I made in my previous post. Do NOT try and rush your reps. You goal here is not to move quickly, your goal is move in the right way. If you try to move quickly, you will not be able to control and coordinate the movement.
Andrew,
There are a few problems with that video. I've said it many times in this thread, it is a terrible idea to pick random videos from the internet as an exercise reference.
Edit: I hope you don't take that the wrong way, your points were good! It's just that it's very difficult for people to identify good resources, and there is a lot of bad information out there masquerading in nicely produced videos.