While it is not new that Youtube videos can be downloaded to a local drive, now you can convert the format to a Windows or Mac friendly formats even before downloading the videos to your local drive.

This has been done using expensive software in the past, but now it is done online, and for free.

To do this, you can visit http://www.vixy.net/ provide the link to the Youtube video that you want to download, choose the format that you want to download that video in, which currently supports AVI for Windows (Divx+MP3), MOV Windows and Mac (MPEG4+MP3), MP4 for iPod (MPEG4+AAC), 3GP for mobile devices (MPEG4+AAC), or MP3 (Audio only), which means that you can even rip sounds, sound effects, and songs from the posted youtube videos.

Please note that on Windows, in order to play the AVI files you must have a DIVX or XVID codec installed.

I recommend installing XVID codec package for Windows from this location.