I enjoy the six-part Jonathan Larson/RENT documentary found on disc 2 of the RENT film DVD. I believe it's over an hour long?
Independently, I favor BROADWAY: THE GOLDEN AGE above all else.
"The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet."
--Aristotle