Betaflight Camera Uptilt Compensation (roll_yaw_cam_mix_degrees)

Discussion of the Betaflight roll_yaw_cam_mix_degrees feature, which causes the flight controller to automatically cross-coordinate rolls to negate the effect of camera uptilt.
I should also say that, when this feature was first proposed, I argued against it. First, I argued that gyro board align could be used to accomplish the same thing, which was flat-out wrong. And then I argued that the copter would not have sufficient yaw authority to make the feature useful. And it turns out, I was also wrong about that. So I just want to set the record straight that I was wrong, and the guy(s) who proposed this feature were right, and credit to them for pushing it.