Why? It can be kept secure - the tapes are taken back to base and handed over along with the paperwork. It's probably more secure than the paperwork itself, as no one can just glance at it. Another possible advantage of having these cameras around - if there's something visual the first responder needs a 2nd opinion on, they could send a photo to a doctor somewhere. Whether there are actually cases where that's likely to come up, I don't know; someone more medically minded might be able to say.