Though many new media formats are coming up, AVI still the mainsteam of the vide files. It can be played on most of the video players. And then FLV video becomes another popular format on the Internet. YouTube Video, Google Video, Digg Video, Yahoo Video,, the video on the Internet always shows like .flv file as it was much more smaller the avi and other videos.

There are many free YouTube video downloaders, online or offline, if you don't know one, recommended you this -- Cucusoft YouTube Mate, you can free download YouTube videos. It is also a YouTube Video converter and YouTube player.

While you downloaded the flv files, it is a big problem to play it on the some video player, and then you will need a YouTube Video Converter. For Mac users, you need a FLV Converter for Mac

FOR PC USERS:

YouTube Video Converter

FOR MAC USERS

FLV Converter for Mac