Using VideoLAN Player for playback in MythTV (otherwise known as VLC Player) for all video files or certain video files.
The subject is covered in the Official MythTV Wiki (MythTV VLC).
The location in the Front End is:
- Setup, Media Settings, Video Settings, Player Settings
Note: VLC Player exists without playing video. UNRESOLVED.
The reason is due to the way MythTV uses STORAGE GROUPS for your video files (those not recorded using MythTV). If you have MythTV configured to access a path containing video files (such as a LAN path or NFS path, or even local) the MythTV Frontend sees this in a Storage Group. SG = Storage Group. MythTV will not allow Storage Group content to be played with an external player such as VLC. (Yeah this is a sucky deal and a strike against MythTV.)
For example, /var/lib/mythtv/videos is seen by MythTV and sent to the external player as myth://Videos@localhost, which is a storage group path.
further research and reading