On the "why film?" question there's another angle other than confrontation/preaching/etc..
Went out on a quick tootle to Sainsburys to take the recycling, just as an excuse to try out the newly purchased cam - not the nicest of days to do so but new toys must be used straightaway, instructions read later.
View: http://www.youtube.com/watch?v=LG1O31pKA1c
Nothing to write home about, the car pulling out was a minor niggle, not like it was dangerously close, just something a non-cyclist wouldn't understand, the loss of momentum when the road slopes up, and it was obvious he was going to go anyway from his nose-out positioning.
No, the real thing I noticed when watching an incident-free ride was my poor positionng in one short section. Only watching back do I realise that I lost my confidence to keep up with traffic and without realising it, edged to the side, not far enough to make a clear path for an overtaking vehicle but enough to open the door to a close pass.
The following car didn't succumb to temptation and no-one was held up since I was keeping average pace with traffic, just at the cyclist's constant(ish) pace rather than the car's erratic speed-up-slow-down pace.
I only did it the once but the value of the footage is there, for me, to acknowledge my own mistake and bear it in mind. Hopefully then lessening the number of "angry" videos captured by the camera in future...