I think they will have got that information from the contemporary documentation. If they did get that information from there. I'm surprised they didn't have it before the previous news update though. So it sounds a bit dodgy to me.
If I were you. I'd email Mark Gleave and ask him.
Did anyone watch the programme about the titanic last night. It showed the ROV looking around the whole of the Titanic wreck. The Titanic was at a depth of about 12,500 feet, or almost 2 1/2 miles. I'm not sure how many metres that is though, but it's very deep. The ROV was able to access places you wouldn't think possible and film it in good quality colour film. It gives an idea of what can be done. The ROV was right inside the Ship looking everywhere.