At 7:00 in the video the protesters pushed the fence a couple of meters forward and almost broke the police line, that is not peaceful protesting. Pushing up a blockade against police is very aggressive, and can't be done by a single bad apple either. If protesters had been acting like this for hours then it makes sense that the police sprays them.
https://www.facebook.com/jessica.bundy.79/videos/36571421876...