I'm glad that no one was hurt (even including the jerk) and little bit wiser (hopefully) after this incident.Unfortunately, nothing ever good comes from these kinds of things. Be grateful that brush DIDN'T turn into a bump and spin and cause some SERIOUS injury and damage - from the sound of it, it could easily have been a whole mess. Everyone above has contributed some positive advice. Stay calm, speak of the facts, admit to no wrong-doing - ever. Your insurance company will process everything unless or until you are charged and need to show up in court. Dispute with them what you can prove or counter claim - if he has no witnesses, it will become a mutual draw. DO NOT admit fault just because you were making a move - that doesn't yield the road or other 'common courtesy of the road.'
As for cameras, consider them an almost necessary thing these days - just take a look at the Russian roads and their driving behavior - it's UNBELIEVABLE and most folks just drive off and leave it to their pocketbooks (if rich) and insurance companies if they even have one. YIKES! Try blackboxmycar.com, perhaps a bit pricey but some of the best hardware out there...
As for the camera, I placed an order for blackvue and power magic pro (timed hardwire kit). I will attempt to install the camera myself (I think hiding the wires under the A pillar is the toughest part).