UnPlug. I’ve got to say, one of the ugliest Firefox extensions I’ve seen, but it appears to work as advertised. Lets you download video which is embedded in a web page.
UnPlug is different from the VideoDownloader extension – The Videodownloader extension takes you to the videodownloader.com website, which then tells you where the video is kept based on the website’s address. UnPlug will search what’s on the page for where the video is using a few different methods. It can also ask videodownloader.com or keepvid.com for their help too.