It's not just the noting of series of number plates at one location, - it's at many locations simultaneously, and because it's always happening the system that

It's not just the noting of series of number plates at one location, - it's at many locations simultaneously, and because it's always happening the system that "notices" that vehicle AB123CDE that passed point A at 10:26:32 must have been speeding (or jumping red lights - also under surveillance) to pass point B at 10:29:41 can flag up the relevant series of videos for a humans attention.