In this connected world we all have to be concerned about copyright and fair use issues. It is , not just what the patrons will do with the content but the libraries themselves; especially when it comes to public presentations, handouts and teaching materials.
American University's Center for Social Media has a page that deals with issues about copyright and Fair Use. The site contains downloads of guides, articles and videso that help to explain the concepts of what you can and can't do with copyrighted material. Peter Jazsi has a simple list of what you can do such as able to use any U.S. government documentation without permission and that include text, audio content and videos.
What Works Are In the Public Domain is a four page chart of what works you can freely use without concern.
There are other places to check out for assistance such as The Center for the Study of Public Domain from Duke University. This is a humorous comic book style guide that will help readers understand issues concerning copyright.
Standford University Libraries has a wonderful page full of just about everything you would want to know about the topic. There is a library resource page that contains links to other libraries that have a specific focus on the topic such as music libraries, rights to rebroadcast DVD and videotape content and more.