From the site:

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.

UnPlug works for lots of sites including youtube.com, ifilm.com, current.tv, revver.com, peekvid.com, video.google.com, mobuzztv.com and lots, lots more.

Unlike many other extensions, UnPlug scans the page, and if it doesn't know there the data comes from it can guess - correctly most of the time.

In this Citizen’s Guide to Creative Commons, we’ll walk you through the various Creative Commons licenses, and explain the ways the different elements of a CC license work together. We’ll cover how to properly use and attribute someone else’s CC licensed work, and general best practices regarding CC licenses. Updated August 2015!