If you don't already know, the catalytic converter is part of a car's exhaust system that helps to reduce the harmful emissions created from gasoline and diesel-burning engines. It has a chamber called a catalyst that the gases and fumes are pushed through and are broken down into less harmful or less toxic fumes before they are blown out the back of the muffler's tailpipe.
So why do some people steal catalytic converters? Well, inside the converter there are some small amounts of precious metals, such as platinum, palladium, and rhodium
that can be sold to metal dealers. Prices vary obviously based on the vehicle it came off of and the person doing the buying but can typically go for anywhere from $50 - $1800 (for hybrid and larger vehicles).
This man was just driving through the neighborhood and noticed the scene unfolding. One of the lookouts shoo's him away telling him to go around while making a half-hearted attempt to cover his face.