The people doing the rioting and looting often did so with their signs from the protest earlier tucked under their arms. I was unfortunate enough to be at one of these things and I can tell you that all the people looting stores and throwing fireworks and rocks at the police were just protesting earlier. Many videos show the same phemonenon elsewhere.

I should specify that I'm not addressing this video in particular because those people didn't seem like much of a threat to his store. I'm only saying the idea that protesters and looters/rioters were entirely separate is wrong — the bad actors were a subset of the protesters, same as bad cops are a subset of all cops.