I have just entered a Release which is a DVD of a live performance (a semi-staged concert, but it could have been a fully-staged opera or musical). The performers had specifically directed movements and actions on stage, beyond the musical sound they made. An Artist was the stage director, and his contribution was so important that he was one of the three Artists on the cover of the DVD (the other two were orchestra and conductor).
Yet, I see no Artist-Track or Artist-Release Relationship which could capture this contribution to the Release. There is Conductor, and Performer, and Legal Representation, but not Stage Director.
In fact, there are several Relationships which describe contributions to the visual aspect of a performance recorded as video, or even a live unrecorded performance: technical director, camera operator, cinematographer, lighting design, set design. But I don't see Relationships for any of these. It seems this absence reveals MusicBrainz's origins as a database about audio recordings, before it took on the goal to "collect as much information about music as we can".
Has there been past Style discussion about Relationships for visual and action contributions, revealed in video and film recordings? I'd like to read up on it.
Then, I expect I'll be back to propose adding Relationships for Stage Director.