[fekker]

Using the fake files information, you could then enter the index for the library in the plot summary and/or plot fields as additional text in the nfo file itself.

Something like
<plot>On Disk #2311 - And this is the plot of the movie</plot>

Depending on what skin and view you use for your collection, I add it to a field that isn't part of the sorting but shows up when you view the movie data without having to choose the movie information. (i.e. I wouldn't add it to genre, title, date.. etc, as those are fields you can sort / filter by)

Another way would be to create a flash movie that pulls the disk id from a file in the same folder (that way you could use the same flash movie, and just change the text for each movie). Then when you play it, it say's something like "Insert disk #"