The Pare Lorentz Film Library at the FDR Museum has a video lending library free for teachers on a variety of historical and environmental subjects. The titles cover subjects from the Dust Bowl to the polio epidemic to the White House gardens over the years. Some are DVD format and others are VHS, and lengths vary from 12 minutes to hours and hours. Details include information related to the target age and any warnings about violence or tough themes. They mail you the videos for free and you have 3 weeks to view them and return them (at your cost).
We have access to a lot of similar stuff through Netflix and the public library, but this seemed like a neat resource for very little cost.