Try downlding VLC (has in-built codecs.) If the file won't play with VLC then chances are you got a hold of a corrupt file. You may need to try again. Try previewing the file whilst dwnlding with LW so you can know if the file is ok or not. But to peview the file it must have at least a few % already dwnlded, the more the better. eg: 1% of a 60 min video file will be about 36 secs. 5 % would be 3 mins. For a movie it should be over 500 MB in size or else it may be fake or poor quality.
If you'er dwnlding recent release material, beware of T1 & T3 sources. See: http://www.gnutellaforums.com/showth...560#post112560