How is the video performance if there's the slightest bit of dirt on the lens shared by the LEDs and the camera lens?

That circle of LEDs doesnt "tell the motorist" anything. I bet you couldn't find a single motorist that thought that was a camera if you asked 1000 of them. Besides it's way too dim to see in anything but full dark.

5 hours runtime is good. However, without seeing the video including nighttime performance with all the lights on and rain on the casing, I wouldn't buy one. Maybe it's great. It's better mounting for a rear-facing camera than we've ever seen before, that's for sure.