There are many regions of the world where the current approach of being able to select a language for sound and subtitles with fallback to english isn't quite good enough. There are for example cases where DVB-broadcasts contain multiple languages where none of the ones available match the language selected for the gnome session. Looking at regular users around here (Norway) I observe.

1. The country formally has two languages (nb_NO and nn_NO). Most people would want to choose their favorite, but prefer the other alternative over foreign languages.

2. Many implementations (eg. some DVB broadcasts and DVD media) still use a common Norwegian language definition (no_NO). When available most people would also preferred this over foreign languages. Whenever this is used, it is always instead of, not in addition to, the two split dialects. 

3. With Norwegian, Swedish and Danish being about as similar as English, Scottish and Irish many people would prefer one or both of these too, before falling back to something else.

The bottom line is that there's a need for common prioritised list of preferred languages that could be shared by all applications. It may not only concern sound and/or multimedia-applications so the prefs may not necessarily belong with sound prefs. Maybe a new tab for language-prefs in the "about-me" dialog would be a better place.

Note! this feature-request isn't specific to totem, but totem is the gnome application where it is most obvious that gnome could use this feature.