open and edit odd .avi

[Empire Earth2]

Ok I know of a program (VLC Media player...) that will open .avi even the odd ones I downloaded. I lost my seccond season of Voyager on DVD so I went to get them from DC++ but when I tryed to open them with windows media play... it said didn't know codec. I also can't edit it in any video editing program I own. They can normaly edit avi's but not the one's I downloaded from DC++ How do I make them compatable? is there a certain specail codecc?