[da-anda]

I see your point. I guess I owe an explanation why it looks as I'm insisting on it

I already got your point and it of course makes sense for large DVD collections to start numbering them, but imagine you'd like to have two different collections (maybe one for bought movies and one for private ones, or yours and the ones of your room mate etc) - there you have to be able to distinguish between those - that's why I think the medianame should be a string and not strictly a number, as it's not flexible enough.

FILES mode: I can open folder and see what disc I have to put Finding.Nemo.DVD.(2005).105 so I just go and grab disc N.105. In order to add such a movie I need only to make empty file and name it properly, no need for making and editing NFOs...

MOVIE mode: Same as above. I can put DVD or HDD or BR in file name if I want, but it's not mandatory. XBMC tells me disc number derived from extension and I decide if it can or can't be played in XBMC. Nothing is stopping me to put it in HDD player if I own one.

As Harry already mentioned, the problem is, that you have to tell XBMC which file extensions are playable movies in order to index them. With your approach you would have to add all numbers from 001 to 999 as playable file extension or tweak a lot in XBMC. So that's not an option, is it?

So, in order to have the medianame/number detectable in the file name, I suggested to prefix it with some special string that's indicating that this is the media name. So instead of:
Finding.Nemo.DVD.(2005).105

you would write:

Finding.Nemo.(2005).#105.dvd (assuming the indicating string is #)

So also no need for a special NFO key, althought this should also be supported. Could you live with this? It's not much different from your proposal.