Actors who play well-known figures have their work cut out for them: They have to create a compelling performance that also rings true for audiences who are familiar with the person they’re playing. Now, imagine doing that with the actual famous person also onstage. That was the tall order given to Christine Lahti, who plays Gloria Steinem in this biographical play. Written by Emily Mann and directed by Diane Paulus, “Gloria: A Life” follows a familiar biographical formula in its first portion, which stages many steps of Steinem’s career — including her involvement with the women’s movement and in the creation of Ms. magazine. But in the show’s second part, Steinem herself steps onstage, and moderates a discussion with audience members about what they’ve just seen. Both parts are in this recording of the play, which was shot during a live performance. In his review for The New York Times, Jesse Green wrote that the play “would make a useful introduction to the feminist trailblazer for those who know little about her remarkable overlapping careers as a journalist, activist and ‘wandering organizer’ for the revolution.” But he added that it “does not have much new to add” for audiences familiar with Steinem’s story.