Dashcams don't currently impact your premiums per se, there are no "discounts" in the traditional sense. Where they hold value is providing an impartial account of events which will often get you out of a 50/50 decision like a sideswipe. There are a lot of people that get handed a 50/50 decision simply because there's no way to prove who was in the wrong, occupants of your vehicle don't count as witnesses. A 50/50 does the same thing to your record as a full blown 100% at-fault so keeping that off your record can be huge.
"Masked Bandit is a gateway drug for frugal spending." - Unknown303