This "long piece" provides a deep dive into the evolution of entertainment industry documentaries, tracing their shift from promotional EPKs (Electronic Press Kits) to raw, investigative exposes. The Anatomy of the Entertainment Documentary

If I had to take a guess, I could try to create a text based on a possible interpretation. For example:

The modern entertainment documentary has moved beyond simple "making-of" featurettes. Today’s filmmakers use four primary Documentary Styles—poetic, participatory, expository, and observational—to peel back the curtain on Hollywood and the music industry.

Documentaries within this genre typically fall into three major categories, each serving a distinct purpose for the audience and the industry.