This video, shot February 3, 2016, shows evidence of intentionally set wildfires in southern Chile. In addition to the pattern of ignitions for several fires that indicate the work of an arsonist, you can actually see a horseback rider igniting fires.
When the black and white images appear, it indicates the camera operator has switched from regular video to infrared, which detects heat. The white areas are the hottest.
In recent days there has been much discussion in Chile about the cause of some of the scores of blazes in the country. At least 43 people have been arrested for allegedly starting fires. More than 400,000 hectares (almost a million acres) have burned and 11 people have been killed, including 4 firefighters and one air tanker pilot.
Again, this video is from a year ago.