Illegal recording is a pretty good rule actually. Almost every party I've been to has a rule against filming dance floors, although in German law it's only illegal to publish a recording "of" a person. The flip side to illegal recording is that it's effectively legal to do silly things without worrying it'll haunt you forever, and that's pretty cool. Note the relatively relaxed attitude to things like public nudity (which is only legal in certain places as I understand it, but still). Almost every Berlin party I've ever been to has a rule against filming.
I think there's an exception for dashcams. Might still be illegal to publish recordings. Not sure.
You can put shutters on a camera so it can't see off your property.
Also you have to tell people they're entering a video surveilled area before they enter that area. Or else you go to prison.
Fancier cameras can have filters on the motion sensor (which I wish I had--mine wasted too much recording time on the wind moving a tree), but you can't exclude the area.