Codecs would be your issue...
Get the VLC player it has all the necessary codecs already installed and can play just about any file...(it's free as well)...
VLC media player - Overview
To make the 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
If you are running XP this codec pac is also very good and handy to have as well...
Download XP Codec Pack 2.0.7.1 - XP Codec Pack is one of the most complete codec pack