Television extras organization

You might want to look into the beta for the new/future Plex tv-show scanner/agent which provides native support for local extras (not just mistreated specials).
Extras can be added similarly as for movies on show/season levels. Episode extras are a bit more tricky for now.

Example:

TV Shows                                <- the folder linked to your tv-show library
  Show Name
    Season XX
      Show Name - sXXeYY.ext
      Show Name - sXXeYY-deleted1.ext   <- episode extra (numbered)
      Show Name - sXXeYY-deleted2.ext   <- episode extra (numbered)
      Show Name - sXXeYY-behind.ext     <- single episode extra
      Behind the Scenes                 <- season XX extras folder
        Gag Reel.ext
  Trailers                              <- show level extras folder
    Show Trailer.ext
  Clean Opening Titles-other.ext        <- other show level local extra (inline)