I must admit that I was not aware of this requirement.
You can have systems and policies and provide training. It is fine to have good safety systems, but there is always a human factor in everything. Sometimes human error is the cause of accidents. If the videos can tell us more about why the accident happened, that's a good thing. I am not aware of why video cameras have been installed in the locomotives.
Unfortunately, I don't have a more precise answer to give you. I can only give you my impressions.