How do I play OGM video files?

I recently clicked a link to download a movie and when I unzipped the file it contained something with a .ogm extension. Windows doesn’t recognize the file. Is this a virus or did I do something wrong?
While it’s always smart to scan any download for viruses, the OGM extension is typically associated with video files. OGM is the Ogg Vorbis video container format, similar to AVI or MP4, that generally contains Ogg Vorbis audio and a video stream that is often DivX, XviD or Theora video format. To play an OGM file, you have one of two easy options.

The cross-platform solution for playing back OGM files on Windows, Mac OS X and Linux is VLC Media Player. VLC supports playback of OGM, MP4, MOV, most MPEG files and most other audio and video formats. The most glaring omission from the list of supported formats is RealMedia files. After installing VLC Player, the OGM video file should automatically playback using VLC.
If you prefer to playback OGM files using Windows Media Player, you need to download a codec pack to add support for OGM to Windows. The best codec pack for OGG and OGM support in Windows Media Player is the RadLight Ogg Media DirectShow Filters After installing the RadLight filters, you still need to associate the OGM file type with Windows Media Player. To make the proper association, open Windows Explorer and choose Tools > Folder Options from the menu. Click the File Types tab and locate OGM in the list (if it doesn’t show up, click new and add it).
Play OGM Video
Click the Change button and Select Program from a list to choose Windows Media Player. Select Windows Media Player from the list and click OK.

Close the Folder Options and any OGM file on your system should now automatically open in Windows Media Player.