It’s probably related but not directly connected. My mind’s eye is almost totally blind but I can have John Williams conducting a full orchestra in my head if I want.
(I can’t ‘hear’ lyrics though and have great difficulty remembering them)
would your friend be able to hum the star wars theme song from memory? it seems impossible for me to be able to recreate the star wars theme song without being able to hear it in my head.
So it's probably like hearing "inner" sounds, just with motion pictures.
I wonder if there are also sound aphantasts, but it's highly likely.
Different to the case described at the beginning of the article I have lots of memories. But they are stories of what happened, not movies.