how to download youtube videos without any softwares

For eg if want to download the below video
http://www.youtube.com/watch?v=U9SmqzLNdzo&feature=youtube_gdata

Step:2
then add "ok"  before youtube
http://www.okyoutube.com/watch?v=U9SmqzLNdzo&feature=youtube_gdata

Now you can download it without youtube downloader or without using any other softwares...

Enjoy...