Video DownloadHelper is a useful Firefox add-on which lets you easily and quickly download videos from hundreds of video sites such as YouTube, Metacafe, or Vimeo.
Whenever you watch a video on any of these sites, the Video DownloadHelper icon located next to your address bar will activate, letting you know which videos on that page are available to download. All you have to do is click on a video to start the process.
The list of websites supported by Video DownloadHelper is quite large. Check them out by clicking on the icon located in the toolbar whenever it is inactive.
The tool also lets you access adult-content websites such as Xvideos, RedTube and PornHub, although its use is limited to adults over the age of 18.
Video DownloadHelper lets you download videos in different formats, such as MPG, MP4, and AVI; or you can extract the audio and then save it as an MP3 file thanks to its FFmeg component.