When I test drove an LS4155 with ag tires, I could get the tires to rub the loader mount just by turning sharply on level ground...
I watched your vid, and I can tell you there is nothing wrong with YOUR tractor specifically. Unless dealers are setting the stops tighter, it's how all the 4-series tractors are... LS should have either moved the axle forward a couple inches or revised the loader mount for better clearance with the larger than normal tires they're using on the 4-series.
While you might be able to adjust out the stops out enough that there won't be any rubbing, doing so will also sacrifice your steer angle on the level. Additionally, using the stops to stop steering travel IMO is how you break off steering arms, since the ram will still be giving her all she's got trying to steer tighter if you're not smart enough to let off the wheel a little when you feel resistance.
If you adjust them, I would make sure that you set the stops on the front of the axle to contact at the same time, or JUST before the stops on the back of the axle. That way you limit steering with the pull side of the axle, not the push side... That is easier on the steering arms if you occasionally hold the wheel against the limit trying to turn sharper...
If it were mine, I'd leave the stops where they are and just not steer all the way to lock when driving in the rough. If you hear the tire going pop pop, straighten the wheel a little and it'll stop. That way when you're on the level, you can still turn sharper.
I would also take a grinder and round the edges where the tire hits the loader frame. You could probably gain a decent amount of clearance just by having a nice 1/4" radius on those square edges, and it certainly isn't going to sacrifice any strength... If you can't be bothered to just not steer so sharply, I might add some spacers to the articulation stops rather than limiting steering angle, or add them first, then limit angle as necessary. Being able to turn sharp at times is certainly nice...
