Bacl in 1999 there was a lot of discussion about cameras in the Cabs, not only on NS but to some extent on CSX as well ( This was during the time frame of the School Bus Crash on the Ga/Tn State Line. Driver apparently tried to beat the train across a rural crossing). AS I recall most of the fear was that the cameras would record in cab conversations, and be used as evidence to punish the individual crews for rules transgressions.
Remember, at this time there were very few cameras installed, and the rumor mills were really ginning up paranoia among the crews who had no first hand experience with a mounted camera on their engines.
Now that approx ten years experience is under their belts, the camers have proved their worth in recording what happens at the crossings, and that the crews have a witness to back up their actions.