"I could get a warrant"... "Go ahead"
It should have ended there period, until such later time as he had a warrant in hand.
The cop's swollen ego just could not let the man walk away. Plus, he probably knew he wouldn't get the warrant, or he would have already had it. He then overstepped very badly.
The fact that the cop told him there was no warrant yet, told the guy all he needed to know that they were done there.
Everything that happened next should be on every cop who was there.
Sheriff maybe should have:
1. Immediately watched the BC footage, and understood that was a civil rights violation.
2. Fired that deputy.
3. Made a statement that such as that would not be tolerated.
Instead, they maneuvered, enlisted the local paper, and tried to weasel it to put them in a good light.