matthew clarks had cameras fitted forward facing but also into the cab, constantly overwriting unless it activated and then it recorded and saved, i think 5 secs before activation 10 secs and then another 5 secs… IMO opinion the principle is good, ie to confirm blame for any incident. However matthew clark management used it to get rid of their staff to a point that you concentrated on not activating camera and not concentrating on your driving… … used to be queues at the end of each shift of guys being told to see TM…