It's annoying when people look at things in a black/white way. The truth is both parties were wrong. The police officer should have spent more time explaining the consequences of failing to sign the ticket. Instead, he asks him to get out of his car and the puts him under arrest. Anyone in that situation would have been taken aback and confused. Had the cop simply explained that by signing the ticket, he wasn't admitting guilt and that he could still contest the ticket in court, and if he didn't sign it, he would be forced to place the driver under arrest. I'm pretty sure, the driver would have signed the ticket at that point.
The driver was wrong as well. When he was out of the car and the cop asks you to do something, you do it. You don't walk towards a cop and ignore his commands. At that point, the police officer was in his right to defend himself. Who knows what this driver was capable of doing. I don't think the cop was wrong for tasering him. Haven't you guys seen Cops? There are plenty of times where the driver acts like he is just casually walking toward the cop only to assault him to get away.
Still, I think the police officer is ultimately responsible. He is the one with the power in that situation. He could have showed more patience. Instead, it was obvious, the cop lost patience with the driver because he argued with him. I'm sorry but that's no excuse to ask the guy to step out of a car to arrest him. He should have done his job by explaining the consequences. The cop didn't want to do that and instead he just wanted to place him under arrest and get it over with.