RMS at TEDx: Introduction to Free Software and the Liberation of Cyberspace
fsf.org
fsf.org
What about this interview instead?
It might be better to explain examples of free software that people may already be using, or things that they might want to use. Perhaps show examples of why for example free access to source code allows poor schools in africa to customise software to their needs etc.
From the text: The TEDx talks are "designed to help communities, organizations, and individuals to spark conversation and connection through local TED-like experiences."
EDIT: it is a "licensed event", but not TED.