Open Source video creation

For the upcoming MythNetTV release I am toying with the idea of asking the user if its ok to include a default subscription to an announcement video blog. This blog could be used to inform MythNetTV users of things like new releases, and important bug fixes if such things happen.

This raises the question — if I wanted to mix creative commons licensed music with some still images (the announcements), what tool is the best to do that? Specifically open source tools please.