I nearly had some great footage for one of these last week.
Going down a 30mph main road, junction on my right about 75 meters away.
A car appears at the junction, looking to turn right - so, head in the same direction I am.
He goes to pull out, but immediately stops halfway into the first lane as a car was coming the other way.
I take my foot off the throttle as its clear fun and games are about to start.
The car he has just stopped infront of, flashes him and waves him forward. He doesn't bother looking at me and just pulls out.
I hit the brakes for everything they are worth, as well as the horn and my lights. He just about gets out infront of me, and drives off as though nothing had happened.
Guy who had flashed and waved him out turns out to be about 90. Doubt he saw me up the road, and drives off also.
That is exactly the sort of accident I'd want one of these cameras for. If I'd hit him, you could bet your bottom dollar there would be all sorts of crap going on the guys insurance form, when quite simply, his 2 failed attempts to get out of the junction highlight just how poor his driving standard was.
I can however understand that if you like to 'play' on the roads, having a dash cam is a bad idea. My solution? Don't play on the roads. Go on track days.