I hate DVD extras -the usual "making of" claptrap, but for a change, this featurette about the play and movie CHICAGO is extremely informative and rewarding.
I think the secret of its success is not to engage in the tiresome "rah rah rah" pats on the back of filmmakers for their crew and cast, but rather a delving into the history of the project and particularly its origins in Bob Fosse/Kander & Ebb's Broadway play.
Only the last few minutes deal with clips from the film; instead we see shots, plus a brilliant musical number taped on stage by the late Jerry Orbach, from the play, and interviews with several of the play's participants. Orbach, Chita Rivera and later player (on the road) Ann Reinking are not self-serving, avoiding that pitfall.
Producer Martin Richards is especially delightful, limning the tortured history of trying to bring a seemingly unfilmable play to the big screen, especially after the untimely death of Fosse (who would have directed it way back when). Richards' very few movie credits as producer make for a quite an eclectic, and quality, bunch.