Check your local and state laws concerning the use of video as evidence. Generally; if local or state government can mail the owner of the vehicle a traffic citation for speeding, running a red light, or failing to completely stop at a stop sign they have camera laws. If they do get a camera and use it. Every time your placed in danger by a careless or reckless driver save the video and file a compliant at the local police station or with the first officer you find. Nearly all police cruisers have computers with a memory card reader and can copy your video evidence. They will in turn send the vehicle owner a traffic citation or in the case of reckless driving or reckless endangerment a warrant for there arrest and detainment will be issued. After a few weeks people that don't take there driving seriously will quickly learn too start paying attention. Some will even come to the realization it was the cyclist with a camera that caused that expensive traffic citation to appear in there mail box and there after treat every cyclist as if they were a policeman.