This is the reason why I don't feel qualified to pass judgment on anyone in the video. I wasn't there. I can't see what happened before, after, or not shown during the video.
I have worked at a number of demonstrations. I would try to do everything I could, within reason, to provide a peaceful opportunity for everyone to protest and speak their mind. It was often obvious that not everyone was interested in peaceful demonstration. Many people were there solely for publicity. Some people were there to bring about a conflict either with counter demonstrators or the police. Often the permit issued for demonstrations in public spaces are very specific on what is allowed and where it is allowed. There are many things that go into these types of permit issuance negotiations. Sometimes people show up to demonstrations on either side who have no knowledge of or consideration for the lawful process to provide a free and peaceful protest area for as many people as possible.
Some people think that their individual rights out weigh the rights of everyone else in the entire country. IMO, those people are just plain wrong.
Be safe.