There is no separate metadata source for concert recordings. The only usable for Plex anyway is TheMoviedatabase, which lists concerts as regular ‘movie’ releases. So there is no sense in using a different notation than for movies.
So you will have to use a ‘Movies’-type library. (which is not the worst choice)
It doesn’t have to be the same library where you store your regular movies in. Plex allows the creation of more than one library of each type (unless you are using one of the Android-based WD NAS’s).
You can use Collections to tie your concert “movies” to your music artists or albums in your music library.
And since a Movies library also allows bonus content to be included, you can also add the bonus videos from your concert DVD or Bluray.
