I've been recording for 6 years with a helmet cam, which can record events to the side and slightly behind, like a menacing car, if I turn my head I haven't had a major incident yet, so it has not been helpful with that.
What is has been helpful with is making me a better rider, as early on I discovered that any outbursts and over-reactions were rather ugly. Also I get to document and share the joy of bike commuting and other rides.
https://www.youtube.com/user/bgvideo62/playlists