I had "acceleration shifts viewpoint" set to 0.005 m on both videos. I don't like having it any higher 'cause it makes it look like the seat's broken or something when driving the open-wheel cars.
The view wouldn't stay locked on the horizon if you're on a hill. It'd point towards the direction the vehicle was moving, which would be downhill if you're driving downhill. And yes, the "demo" video I made was rather extreme, I'd suggest it be adjustable in a range between the current "fixed to the car" view and completely unlocked. Something half-way between would probably look much better than all the way.
It wouldn't look into the corner like with the look with steering option.
If you then hit the brakes while moving the car will pitch nose-down. On the current camera system the view will stay fixed with the body of the car and show the horizon rising. With my idea, the horizon would stay level and the car body (dash and interior) would rotate downwards, which more approximates what it looks like in reality.
When making a right turn, the car will lean to the left. Again, in LFS as it is now the horizon will appear to rotate to the right while with my idea the horizon would remain level and the interior of the car would roll to the left.
You could also add a yaw function which would make the view move towards the actual direction of travel which, if in a skid, would actually be in the opposite direction of the "look with steering" function, but I don't know if that'd be annoying or helpful (it could provide better feedback as to when the car is oversteering.)
If implemented you'd probably want to include some kind of scaling adjustment so you get a mix of rotating horizon and visible body roll.
In "real life," when the car leans and pitches from turns and acceleration/braking your vision is focused on the track and world outside the car, and thus the body of the car is what appears to be moving, not the rest of the universe.
However, in LFS the camera pitch, roll, and yaw are tied to the vehicles own axes so that the camera stays fixed relative to the body of the vehicle making the cars movement seem unnatural.
If the camera was tied to the direction of movement (with an adjustable amount of smoothing and/or multipliers) I think it'd look much more realistic and give a better sense of motion.