I'm going to post cctv to facebook showing the person and their dog who has been pooping in peoples gardens
Why would you post such a thing?
The owner is mean and doesn't bother to pick up after his dog.
While I don't think this is the right way to go about exposing him, I do agree that he is in the wrong in this situation. He should be picking up after his dog.
Man, I'm going to ruin his public image and post it like nothing.
Before you make the post I think you should confront this person and try to work things out in private.