Matthew, I know you take this very seriously and are trying to do your bit to rid North Wales of dangerous road users, but I do not believe this is the way.
I may be wrong, but I do not see any constructive or positive outcome from this sort of behaviour.
Whether the policeman was right or wrong, your behaviour (as described) makes me feel slightly uncomfortable.
You've stopped verbal interaction with transgessing motorists, which is a Very Good Thing.
You've stopped shouting the speed limit at passing motorists as you film them, which is a Very Good Thing.
You've stopped loudly and audibly reading out the registrations of transgressor vehicles as they pass you, also a Very Good Thing.
I now heartily recommend that you stop photographing 'phone users stopped at lights and offering the pictures to constables on the beat.
Such behaviour will not speed your entry into the ranks of PCSOs.
Keep riding your bicycle and keep making those charming short films of your commutes... There is no vacancy for a Captain Rhyl, Street Avenger.