Hehehee... lol !!! XviD is not a virus but an open-source third party decoder which enables the user to play movies in formats like DivX or DivX coded .mkv or .avi files.. Have you tried opening the file with Windows Media Player after installing XviD ?? If not, do it. If it doesn't work... Uninstall XviD (do the hell with it) and install VLC Media Player... Now enjoy all your movies on VLC !!! Don't worry, it is free and small size !!
Regards,
Preetam Das