[mythtv] MythVideo internal player filetype case sensitive

[Anduin Withers]

> Actually Video media playback, (i.e. ripped dvd's) where defaulting to a 
> mplayer config, but I switched it to "Internal" and it worked pretty good 
> so I kept the Internal setting instead.  That's svn head as of 2 weeks
> ago.

Actually ripped/transcoded (.vob/.avi) should have been covered. mplayer is
still the default player in that any file type without an explicit player or
any type with the "use default" checkbox checked would use it.

-- 
Anduin Withers