Earlier quoted context omitted.
Sounds like relations between these two neighbors is already pretty bad -- the guy crosses the street to walk on the other side? Because he was asked not to point his security camera at someone else's property? Some people are just... children.
Wait til you see two neighbors arguing about property lines.
The line between "please don't point your camera onto my property" - something I would respect as a courtesy regardless of the law - and "I'm going to cross the street not to interact with this person" goes straight through mental illness in my opinion. Normal, stable people do not behave that way.