Firefox Add-on: Video DownloadHelper

This is a great add-on for Firefox which enables you to download videos from sites like YouTube. It also works with image. This add-on adds a little icon on your toolbar and when you are on a page containing links to images or movies, you can download some or all of them at once. Works with Firefox versions from 1.5 to 3.0.

Homepage: https://addons.mozilla.org/en-US/firefox/addon/3006