Israel said a man who family identified as Pierre [the black man] was arguing with a woman. When the deputy responded, Israel said, he was attacked.
You first see that the cop was barging into Pierre's house uninvited and escalating the situation. An argument developed. Then you hear Pierre ask the cop "What did you say?". This means that the cop said something to Pierre, making him angry. And Pierre said "Say it again" to the cop. And the cop then angrily shouts something to Pierre, escalating the situation, making Pierre angry.
And why is the body cam footage blurred? Are they trying to protect the female damsel in distress? Or are the police trying to cover up evidence that the cop provoked the situation? Maybe the cop assaulted Pierre first, making Pierre angry, leading Pierre to retaliate against the cop.
When Pierre attacks the cop, the cop tases Pierre, making Pierre more angry. The cop continued to tase Pierre even though it does not work. Tasing him will only make Pierre more angry.
His family even said "He was a loving, caring person. He loved his family, he loved his kids. This devastating to all of us, and it’s not making sense at all."
Maybe the cop misunderstood Pierre. When Pierre first answers the door, Pierre asked the cop "Why are you here? For me? For you?"
Maybe the cop misheard his words. "For you" sounds a lot like "Fuck you". The cop might have believed that Pierre was swearing at the cop.