The talk would describe what parties are involved in a free software project, how a project can start, how it develops and mature. Actions, reactions and motivations of all participants will be layed out to show how the participation in a free software project is benefitial to all sides.
Also a bit more of the economical foundation behind the free software movement can be described if that does not go out of the common line of talks too much.

I have given this talk 3 times before to groups of 30 to 150 people in Latvia, with good success.