I always have my helmet camera on. Not for vlogging or anything like that, but purely for crash / insurance purposes. I had one big crash, lucky with several witnesses and I managed to memorise the numberplate of the woman before she fled leaving me lying in the middle of the road with several broken bones so I managed to sue her and get payout. If I hadn’t managed to memorise that plate she would have got away free and I would have been fucked.
Helmet ca is purely insurance against that happening again. Commuting on the A406 I see enough dangerous driving that I see it as common sense.
I have mine mounted on the top of the helmet, to be honest if I managed to flip and land on my helmet at that point I don’t think I would have a neck left anyway, camera or not.