I found the youtube downloader too slow. So, I found another way out.
I opened youtube, let the full video be streamed. Then I went to the temp(temporary) directory & copied the video file after the full video got streamed.
Upto 50% quicker!! Works same ways with Windows. All files are copied to the directory, even the pictures you view on a webpage. They are erased as soon as you close the webpage.
In Linux, the directory is /temp. Find out the flash video file(.flv) or try to find the file whose size is increasing & is of size suitable t be the video file. Try playing it by VLC player.
For Windows XP, the directory is C:\Documents and Settings\User\Local Settings\Application Data\Mozilla\Firefox\Profiles\8axcg82l.default\Cache for Firefox. …./User/….may also have your own username. Just find the file of increasing size. Rename as <filename>.flv if you don’t wish to select the program used to open it repeatedly.
Sadly, the cache of Google Chrome is cached & you cannot copy easily from there.