Hey, I watch cops.
Showing police pictures on a camcorder really does help to establish who the aggressors are and who's telling it like it is.
And their reactions to being recorded will likely make it clear that they're being recorded with their full knowledge.
Before hand, I'd look into restraining order options which, I believe, prohibit vebal assaults from off your property.
Not for random incidents, but might be useful for continuous problem neighbors and wouldn't be without risk of some sort of retaliation. But doing anything at all to combat the problem would have risks.
Don't think I'd leave my yard to confront them and become a willing combatant in the eyes of the legal community should things escalate.