Many modern browsers will play video (Theora and WebM) and audio (Vorbis) files from Wikipedia, no modifications needed.
For users with unsupported systems, this page contains instructions for installing audio and video software. To set up your system to play these files, find your operating system (Microsoft Windows, for example) below.
Most Windows users will already have Windows Media Player installed on their computer. If you don't have Windows Media Player, or you want to use a different player, please install one from the list below. Otherwise, skip to step 2.
Many recent free Unix systems are able to play Vorbis audio without any installation. If you don't have any audio software installed, use your preferred packaging system to browse the players list and pick one. For example, you may install Totem, Amarok, MPlayer, xine, VLC media player, XMMS and others.