ClipGrab is a free GPL'ed software for downloading online videos.
With ClipGrab you can download online clips from many sites with just
some clicks and then automatically convert them into "usable" files.
This way, you can watch your favourite clips again and again wherever
and whenever you like. And since ClipGrab can also save your videos as
audio files, you can also put them on your mp3 player if you like.
At the moment, the following sites are officially supported:
- YouTube
- Clipfish
- Collegehumor
- Dailymotion
- MyVideo
- MySpass
- Sevenload
- Tudou
- Vimeo1
To install, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command below.
sudo add-apt-repository ppa:clipgrab-team/ppa
sudo apt-get update
sudo apt-get install clipgrab
I installed it using the above on my system, and here is what I get:

and when I click on it this is what I get:

1Source:Ubuntu Geek