Download youtube flv using Download Helper Firefox extension

DownloadHelper is a Firefox extension for downloading files embedded in Web pages.By default, you should normally see the icon at the right of the address bar

Steps:

1) Open Firefox

2) From there install the DownloadHelper Firefox extension just by putting the following url in the address bar http://www.downloadhelper.net/install.php

3) After installation of the extension, restart the Firefox window(s). Now you can see the DownloadHelper icon right of your address bar (like in the picture). So from now, whenever you watch video(s) on sites like youtube.com, metacafe.com etc , you can download them at that point by clicking on the DownloadHelper icon (as shown in the picture).