erik_carlson: Nice work! I believe you are doing much more right than wrong. What follows is my break-down.
Very flat spine
Bar stays close to your body
Bar path is good, not perfectly vertical but very close
You appear to be in control of this weight
You appear to be holding your breath and staying tight for each rep
You say your back feels good. Feeling good is good.
Difficult to see from this angle, but I believe you may want to narrow your grip so that your arms are nearly vertical. The wider you grip the bar, the greater your range of motion will be, making the lift more difficult
Already mentioned by Th3Pwnisher, footwear matters with the deadlift. Try it in Chuck Taylors. Try it in just socks. I enjoy shelving my dignity to lift in a pair of hideous Vibram toe shoes, which now have a permanent stench to them. Squishy shoes are not the best choice.
Also mentioned by Th3Pwnisher, get your hips into the lift. Conjure up some violence and vigor and thrust your hips with purpose on the lockout. It is okay to get a little angry on the deadlift.
Your torso seems to be rotating a bit, as evidenced by the bar's swinging motion on your last 3 reps. If you are using a mixed grip, space your supinated hand about a centimeter or so further out from the center than your pronated hand. This will help eliminate that bar movement that gets progressively more noticeable on reps 3, 4 and 5.
This is not a "wrong", but you may want to try pointing your toes out just a bit. I've found that this helps me get more hip into the movement.
The wrongs are minor compared to the rights. There is nothing in that video that tells me you should take your foot off the gas at all. In the meantime, listen to your body. Add some weight to the bar. Eat well and sleep, all that stuff. Keep working to improve however you can.
You are a fine deadlifter who has plenty room to improve, which is true for most people who train the deadlift seriously!