On the basis that the 'Neighbours From Hell' producers seem to be able to find endless scenarios to film, we have to understand that neighbour disputes can, and often do, reach ludicrous levels of animosity, and commonly end in violence.
We are a territorial species, and the notion that someone is 'messing' with our personal space can bring out the utterly unreasonable in the most passive and thoughtful of people.
It's easy from the sidelines to accept that incidents like this look simply petty and stupid, but as advised, i doubt this is the only dispute going on, or that it has just happened.
Actions like this usually occur after months of years of attrition, which build up without either side really understanding how out of hand things now are.
I have always made every effort, almost all successful, to secure good relations with any neighbours - it saves this sort of grief and nonsense - who needs it!