So after watching the full video and reading the full story, these kids are probably for the most part over-privileged heads and they were definitely mocking Phillips, but this is being blown out of proportion as a much bigger deal than it really is. We have multiple football and baseball teams, at the pro and collegiate level, with cheers that mock Native Americans (not intended to be a complaint about those teams, just saying you shouldn't fault a bunch of high school students for engaging in behavior that's been as normalized as fake Native American rituals has).
The black Israelites were clearly the ones instigating everything and I'm not going to hold it against a group of high school students for reacting when people are yelling vile at them and calling them inbreds or future school shooters. I'm also not sure what Phillips' hope was when he walked over to them and started playing the drum, there's no logical explanation for why that would be expected to de-escalate the situation.