John Marchenko is the stocky/burly young man in the black Adidas jacket who attempted to talk some sense into rioters who were vandalizing an overturned smart car. Several rioters were hitting the smart car with metal clubs and skateboards when Marchenko came on the scene and yelled "this is our city! ... What's the point of rioting?" and tried to get the rioters to disperse and leave the car alone. He also prevented a rioter from setting the car on fire, yelling, "Why do you want to light it up?" and threw a haymaker punch (which missed) at the rioter hell-bent on lighting the car on fire. Marchenko later attempted to prevent rioters from flipping over a van, proving he has balls of steel.
John Marchenko was a true hero during the Vancouver riot.
* Here is another view of the confrontation between Marchenko and the rioter attempting to light the car on fire.