Windows Media Player[Sample|Source|Documentation] Description C1LightBox supports hosting media played by Windows Media Player. If the file URL ends with the following extensions, a Windows Media Player Object will be created to play it by default: ".asf", ".avi", ".mpg", ".mpeg", ".wm", ".wmv". You can also force the LightBox to use the Windows Media Player explicitly by setting the Player property to "Wmp".