It could be a contemporary performance piece designed to be viewed as a "leaked" or "archived" Skype call. The portion of the filename is not a standard video extension (the file itself is a .mov ), but might stand for: National Theatre Board (or a similar arts organization)
While it is not a widely known "standard" file (like a system driver), it is most likely associated with one of the following: 🎭 Performance Art or Monologue
Record and play back a Skype for Business meeting - Microsoft Support
(often used for sharing script-related media) A specific project coder or artist's initials 🎵 Music or Music Video