I have always wanted Google to allow users to download YouTube videos on their phones, mobile etc but perhaps due to some unexplained issues Google did not allow it until now. Other ways like downloading the FLV file and then converting it to a mobile compatible format is just too complicated and does not always prove to be successful.
The good news is that now you are able to download YouTube videos as MP4 files which work smoothly on any mobile device or even on your iPhone. The trick was discovered by GoogleOS and follows the recent code change at YouTube which allows users to watch High quality YouTube videos.
To download YouTube Videos as MP4, add a bookmarklet of the link below by clicking on it and then dragging it to your bookmarks toolbar (in Firefox)
Now whenever you want to download a YouTube Video as MP4, simply go to the video page and click the bookmarklet in your bookmarks toolbar. You will see a link popup in the right information box saying “Download as MP4”.
Right click on the link and select “Save as” and remember to save the file with .mp4 extension to make it work properly.
I tested the trick and downloaded a YouTube video as MP4. It works like a charm on my Nokia N95 and iPod Touch.