As a social studies teacher, I often would show videos in my classroom to provide a visual to the content that I was teaching. Most main stream movies are good additions, but you might often run into students who have watched them. Documentary films provide all the good information without the impact of Hollywood. Below are two directories for documentary films.
Documentary Tube is a directory of videos that you can find on other websites. You won't find videos housed on the site, as this website will point you to other websites where you can find the films. Users can use the search tool or can look for videos based on categories. Users can search the top 100 as well. If interested, users can also suggest a videos to add to the Directory Tube.