Actually there are many ways to download videos from youtube or video service in the ubuntu system, Begin from the command line foo, application, use the browser addons that integrate with desktop applications. There are applications online downloader and converter videos that you should try on your ubuntu system that is clipgrab
ClipGrab is a downloader and converter online videos like YouTube, Clipfish, CollegeHumor, Dailymotion, MyVideo, MySpass, sevenload, Tudou, Vimeo. With a simple interface and user friendly clipgrap have capabilities that are not inferior to any other video applications downloder in the case downloading video.
ClipGrab can also download HD videos from sites That have support for High Defeniton videos (HD Video). You can search your favorite video under the search tab, and then download it to your computer with the format and quality of the video you want.
Clipgrab can convert your videos into the following formats:
Install ClipGgrab in ubuntu 11.10 Oneric Ocelot
The first you have to do add this PPA ClipGrab in the ubuntu 11.10, just type the following command in terminal:
sudo add-apt-repository ppa:clipgrab-team/ppa sudo apt-get update sudo apt-get install clipgrab