A lot of video files are fakes. They will not download atall. If you control/click on a file in search > advanced you will see look up with Bitzi. This will take you to the Bitzi web site and you can see if there is a review for the quality of the file. Go for files with something like 20 sourses would be good advise.
Codec advice is available here,
http://www.gnutellaforums.com/showth...threadid=40665 but a player which does not require codecs is VLC available from
http://www.videolan.org/vlc/ Some Mac users also use "MPlayer"