Commons:Media help/Unix
Browser support
The latest versions of Mozilla Firefox, Google Chrome, and Opera are able to play sound files and videos without any additional codecs or software.
Requirements
If you are not using one of the above web browsers, you may need to install replay software. If you don't have this installed, you can choose e.g. one of the following programs: Totem, Amarok, MPlayer, Xine, VLC media player, BMP, XMMS, or choose something else from Category:Linux media players.
Most Linux distributions have something included that will play Ogg Theora - check for any of the above applications.
Download video codec
Now you may have to download the Ogg Theora codec for videos. However, as most modern distributions and media-players have the Ogg Vorbis codec pre-installed, you may not have to download this.
If you use "MPlayer", "Xine" or "VLC" to play, you do not need additional codecs for Commons media files. Try it and you will soon find out if your system is already compatible with Ogg Vorbis and Ogg Theora.
If it is not you can download the Ogg Theora codec here. Download the file of your choice and install it with your package manager.
Do you have additional questions, or did you encounter problems? Ask here.