I've been working on correcting my deadlift form and I recorded a couple more videos of light attempts trying to put together all of the advice I got:
Obviously some pretty light attempts (36% of my best 1RM), but I'll probably be working around this weight for a little while just trying to re-groove the motor patterns. I wasn't able to spot any problems aside from some cervical hyperextension, and a small "twitch" in my lumbar area before the first lift - I don't really know how to quite explain it, but it looked pretty minor and didn't happen in the other one.
I know I'm a lot less experienced than most of the people on here, so if anyone sees any issues with my current form, please let me know.
I also oriented my training around fixing my anterior pelvic tilt, because I think problems in my static posture point to obvious muscle imbalances. Almost all glute/hamstring and core training with a lot of stretching, soft tissue work, and mobility work. Also a lot of scapular work and rowing to help my back.
Thanks to everyone who gave me advice - a lot of it was really helpful (especially RhinoJockey's diagram!). I'm looking forward to being able to put up big numbers without contributing to imbalances and heading toward injury.