In my neck of the woods there would have been a gang of people pushing on the back bumper. Or...since every 5th vehicle around here is a beat up 4x4 farm truck....I would have gotten pushed or pulled out using my tow strap.
You cant stop someone from filming you. All you can do is be as boring and polite as possible. They are trying to provoke a response, so don't give them one. Smile and say "have a nice day" and carry on with your business. Repeat as often as necessary. This will prove to me more frustrating for them than it is for you.
If you ever come up to my personal car and punch my window out in an act of road rage, you had better hope that I am able to back up or drive away. Because if I am boxed in and unable to get away from you, its time for "plan B" and you aren't going to like plan B very much.