Your friends neighbor installed security cameras directly watching your friends property they have a dispute is this legal?

Probably not. If the camera is watching an area that is open to public view then there is no expectation of privacy, anyone can watch what you do on the front lawn. If the camera is installed so that it specifically looks in to an area that is not in public view, or in to a window, etc., without a specific lawful purpose, it may be something that is against the law.