When the Settings - Audio - MPEG-4Process iTunMOVI for files with video option is enabled, the roles which will be correctly mapped for iTunes and TV display are Director, Codirector, Producer and Screenwriter. Other roles will be retained but will not be recognized by iTunes and TV.
Musician Credits
The 'Musician credits list' is intended as a mapping between instruments and the musician that played it. The field consists of multiple lines specified as: instrument=musician{,musician}.... When the data is saved to files, empty lines and unnecessary whitespace is automatically removed.
When the Settings - Audio - MPEG-4Process iTunMOVI for files with video option is enabled, the instruments which will be correctly mapped for iTunes and TV display are Actor and Cast. Cast is a synonym and will be displayed the next time the file is loaded as Actor. Other instruments will be retained but will not be recognized by iTunes or TV.