******* Codecs I'd say....
Try getting the VLC media player as it has all the codecs already installed and plays just about anything...(and it's free)
VLC media player - Overview
To make VLC your default player...
Go to your shared folder (outside of Limewire) you will find this folder by clicking on one of your files in your LW library and clicking explore...
Right click on one of your video files
Select open with
Select choose program
select VLC
and tick the box that says always use this program to open this file type
Select OK