World of Warcraft also known as WoW is the most widely played online multi-player network game. According to my little knowledge there are over 4 million players registered on the Blizzard network who play WoW. The game is developed by Blizzard Entertainment and is only available for Microsoft Windows and Mac OS operating system. The users of Linux are quite dejected with that. But now I can give you a solution to run WoW on Ubuntu Linux.
Playing video files of different types is a problem for the generic Windows Media Player. You need different codec to play files such as .avi files which are converted using XViD or DiVX or any other such type of encoders. So VLC Media Player (VideoLAN) is one of the best players that I came across.