How to download Youtube videos in mp4 format without using any software.

hey friends........here is a cool trick to Download Youtube video in mp4 format without using any software or any website using a simple javascript.
This script let you download Youtube video directly from the website without any delay.
Below is the code to download a video from the you tube,copy-paste this code into the address bar when your desired video starts buffering.Isn’t it amazing script??? I have attached a screenshot of the video also.
copy this script into address bar:

javascript:if(document.location.href.match(/http:\/\/[a-zA-Z\.]*youtube\.com\/watch/)){document.location.href=’http://www.youtube.com/get_video?fmt=’+(isHDAvailable?’22′:’18′)+’&video_id=’+swfArgs['video_id']+’&t=’+swfArgs['t']}