Lights, Camera, AP HistorySteve Heimler of Heimler’s History helps thousands of high schoolers study for their AP exams, all from his home YouTube studio. That also happens to be the number of people subscribed to Heimler’s History, a YouTube channel that posts AP exam review videos on U.S. history, world history, human geography, government, and European history. After graduating in 2003, Heimler used those communication skills first as a pastor, having started a small church in Roswell, then as a history teacher. I taught AP U.S., AP World, AP European, AP Government.” Steve Heimler For Heimler, all that effort is worth it, and not just because of his growing subscriber count.