How to Download Video in Youtube without using application

here's a very nice trick to download your favorite video from youtube without using any software all you need to put is OK after wwww.
for example the link of the video is

http://www.youtube.com/watch?v=K2y4lujgEVs

all you need to do is like this
http://www.OKyoutube.com/watch?v=K2y4lujgEVs

here is the screenshot..

but is you have Internet Download Manager installed into your computer you automatically download any youtube video by simply clicking the download this video