You don't have to install any software or any application to do this. If you have Google Chrome, all you need to do is just copy the following script and paste into your bookmark page.
Here is how you can download youtube videos using Google Chrome
Press CTRL+B to Open/Show the Bookmarks Toolbar > Right-Click to a vacant space and Choose Add page
Type any text and copy/paste the following code:
javascript:window.location.href = 'http://youtube.com/get_video?video_id=' + swfArgs['video_id'] + "&l=" + swfArgs['l'] + "&sk=" + swfArgs['sk'] + '&fmt_map' + swfArgs['fmt_map'] + '&t=' + swfArgs['t'];


So finally YouTube has launched its operations in India. The site Youtube.in has been launched officially. I don't see any added value except that you have a dedicated domain which only lists videos from India or videos related to India. Google bought the domains YouTube.in and YouTube.co.in last year for about Rs. 2.44 lakhs.



