Youtube does not allow videos to be downloaded, Most sites that promise download of files are sham or ask you to install dangerous software on your computer.
There are documented ways to download from youtube Example Youtube Downloader
youtube-dl however requires installation of python and needs some programming knowldge to use it.
Save video file.com derives inspiration from youtube-dl project,but is not associated with youtube-dl project.
Savevideofile.com is an browser implementation of documented ways to download youtube videos.
Since there are no direct ways to download videos from youtube, savevideofile.com may not be easy to use for some users. This help page helps you with steps for download.
please try with common browsers like firefox or chrome ( I have not & cannot test this in all browsers especially mobile browsers.
go to youtube.com and find the video you want to download
go to savevideofile.com and Navigate to url
You must download within few miniutes for this to work
Copy paste entire content into text box without any modifications
Enjoy your video
Suggestions and feedback welcomeMore Technical Reading @ http://code.google.com/p/youtubesniffer/wiki/Tut3ByGetVideoInfo