I think the 4k/h thing works to a certain extent... purely because people actually THINK about driving, instead of sitting in a car waggling the wheel and levers. I can't believe how many drivers clearly have NO CLUE what's going on around them, or even where their own car is placed on the road.
I have Dash cams, for those who aren't capable of staying over their side of the centre line, and are complete 'tards. They'll either end up with a police complaint filed (had a guy done once already for almost taking my whole family out "testing" his new car, didn't even have the camera then) or on you tube .
I've got some spare cheapy chinese cameras, with an actual working memory card (Apacer) 8GB for $45 posted if anyone wants one. If you buy one somewhere, DON'T use the cheap-arse chinese memory cards that come with them - they usually aren't reliable.
I'm prolly gonna fit one front and back of each car.