Sorry for the facebook link. As always, the video doesn't show what led up to the altercation but there is a version of the story in the description.
TL: DW Barrie police beat the crap out of a teenager for skateboarding on the road (or more likely not respecting his authority)
Edit:
Barrie police provided a non-update (we are aware of video and investigating). Afaik, kid did not receive serious injuries so for better or worse, siu will probably have no involvement.
That's some serious out of control anger right there. Since there were no serious injuries the SIU will do nothing about it, although they would most likely have cleared the guy anyway.
The big challenge in Canada is that while you could bring a private prosecution against these thugs, it will also go no where. From what I understand you can file a private prosecution and present your evidence before a Judge, the defendant does not have to be summoned at this stage. If the Judge deems there is enough evidence to proceed then it has to be turned over to the Crown, who typically just drop the case.
I believe this is what happened to the private prosecutions brought against Fantino.