Wow.. It must be unbearable to have such an a** as your neighbor, that's just disgusting... As you've mentioned, I also realize how important good neighbors are. We just had a new family move in next to our house, and from what I can see, they are
very friendly and I'm glad that's the case. We also have great neighbors across from the street, one who loves detailing his car (we discuss car detailing sometimes), and another who is nice enough to help snowblow our front sidewalk in the winter. It's really awesome, and I'm very thankful for such great neighbors.
As for your situation... I can't believe someone else would have a problem with you mowing their lawn... I mean, I certainly wouldn't mind doing a bit less work

But since he's so insistent on you keeping off the property, I guess you should just keep your own side of your property to prevent further animosity. As BigAl3 said, you certainly don't want to start a feud with your neighbors, it's gonna get ugly. Wow... the more I read, so more I'm disgusted. HE TOOK A VIDEO CAMERA??? That's just.. insane. He barely knows you and he's already looking to take legal action to prevent you from touching his property?
I really feel bad for you, but I don't know how bad it is, so is it really so bad that you are seriously considering moving?