How to download videos from youtube,google video,metacafe without any software

If you watch videos on Youtube or Google Videos or Metacafe,you sometimes wish to save that video and you use a third party software.
Such softwares may be sometimes harmful to your browsers.So why to use third party applications if we have another option.

I am giving list of website with which you can download your favourite video without any software.

Keepvid
VideoDownloadX (formerly known as YoutubeX)
VDownloader
Boom Video
Zilla Tube
TubeG