Aside from the production costs of getting a film crew, and then the production costs of making and distributing the DVDs -- you have to pay the stage director, choreographer, actors, crew, musicians, designers, show writers/composers/lyricists, music director, etc. etc. etc.
Oh, and keep in mind that there is a SEPERATE filming director (Lonny Price was the film director of COMPANY, even though John Doyle was the stage director), producers (which can sometimes be the same producers of the stage show), etc. etc. etc. etc.
So -- if there are any producers out there who wish to lose money, then film a Broadway show and release it on DVD.
(Great Performances filming and airing shows without DVD releases saves some money -- I wonder how much? (ie CONTACT)).
"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