How to download YouTube video direct in 3gp format on computer using firefox to play in mobile without any conversion. Secret reviled

UPDATE

Ok YouTube lovers here is the trick to download 3gp good quality videos direct from YouTube to your computer ( pc ) so that they can run directly in your mobile without any conversion. Please comment your experience after trying this :)

Here i will explain this tut. in steps 

Requirement : Here the most basic requirement is you must have Firefox installed. 

Step 1) Download and install following two Addons from firefox addon store

a) User Agent Switcher

b) FlashGot

There working can be read from download pages so lets go further

Step 2) In Mozilla go to Tools >> Default User Agents >> Choose iPhone3.0 

Step 3) Go to YouTube.com search the video you want to download then click the thumbnail then is will display that video in play box to top. Click the round play button image.

Same time you will see FlashGot (add on we downloaded in step1) blinking

 will show that is has captured a video in 3GP format as shown in figure below just click the video you want then it will start downloading

Thats it ...

Please comment about your experience :)