Rachel Chavkin’s direction is far more concise in the filmed sequences than the overly long live sequences. In what is fast becoming a Broadway cliché for set designers, Riccardo Hernandez has created a classroom set that undergoes a major late-in-the-performance transformation. The scenic coup de theatre is supposed to signal some major change in the story. Unfortunately, the narrative drive runs out of “The Thanksgiving Play” long before Hernandez’s set attempts to stage an 11 o’clock rescue.