The Windows Media Player issue is probably due to codecs. WMP is not set up to play a variety of encoded media. The easiest thing to try is the free media player VLC. it has most codecs installed within it and will play most anything:
http://www.videolan.org/vlc/
A “seed” is someone who has downloaded 100% of the content and is only uploading to peers in the swarm. “Peers” are those who have less than 100% of the content and are downloading from seeds and other peers and uploading to other peers.
Originally (and still in some places), those in the swarm who had less than 100% of the content were referred to as “leeches” and the combined seeds/leeches were referred to as peers. However, because of the negative connotations of the term “leeches”, those in the swarm with less than 100% of the content are now referred to as peers and “leeches” are those who download the content, but do not upload back at least a full copy of the content.
http://www.techsupportalert.com/node/490
The amount of seeds/leechers (peers) has nothing to do with the film quality. They have to do with the speed of the download and generally it is best to have a high seed to peer ratio (more seeds than peers):
http://www.azureuswiki.com/index.php/Good_Torrents
Movie quality is harder to determine. The best way is to read the comments on a release.