simply add "ok" in url of youtube video after "www."
and Press ENTER key or GO button., youtube video can be downloaded.
Its more easy and works without any other site and software installation.
All other sites needs to goto their websites to download youtube vid. But with Okyoutube.com you can download youtube video direct from youtube , without going to any other site other than youtube.com. So we can say that this is the only fastest known method in the world and no other site offers the service like okyoutube.