How is this for starters:

Sir...If you don't comply with my order I will place you under arrest! Move to the back of your vehicle and place your hands flat on the window. At no point prior to the stun gun was the guy told he would be arrested. That usually gets most peoples attention. He then could have explained that signing the ticket does not admit guilt and he had the right to protest the citation in court.

I agree the guy was aggravating the officer and could have prevented this event by being more cooperative. There is a difference between being difficult and being a threat. It was obvious he did not expect the reaction from the officer and wanted to get away from the threat of being stunned. Big mistake. Also...His attitude changed and he was very cooperative after the stun event (expectable) however, the officer continued in a hostile and unprofessional manner in my opinion.

As for being stunned...Yes I have. My wife and I have stun guns we carry in our cars and I had her stun me to show her how to apply it and see the effects. It was not a fun couple of seconds and I buckled like a jellyfish on dry land.

Anyway...The response was overkill considering the video and the fact that he was with his wife and kid.