I do. I have a gopro 3+ mounted to my helmet. I've been recording all my rides for the past 3-4 months. Theoretically would've been great when I got hit a couple months ago, but it popped out and lost the battery and therefore didn't save properly. I was only able to get right up to the accident, not the accident itself. But it at least showed that I was centered in the lane and he had to have illegally crossed the double yellow to pass me, putting him at fault.
I've thought about making a YouTube channel highlighighl all the idiots who cut me off etc, but it's probably not worth the effort. Most people just don't care, especially the local cops, no point at all in forwarding things to them.
I've saved a few things, mostly I just delete.