This was several years ago, so the law in my state may have changed, but I do remember reading that dashcam footage submitted by a civilian can’t be used by police to issue a ticket after the fact. It can be used as evidence for or against someone if the police do get involved, though.

To put it another way, the officer has to witness the traffic offense themselves in order to issue a ticket. But dashcam footage could be used as evidence to prove someone either was or was not speeding after the ticket was already issued.