UnPlug - save video and audio

"UnPlug is an extension which lets you save video and audio which is embedded on a webpage - it's a video download tool.

UnPlug scans web pages and tells you where media players are getting their data from, and displays it as a simple hyperlink: in most cases, you can then follow the simple download link to save the media file."

https://addons.mozilla.org/en-US/firefox/addon/2254