This scene is done using a single sustained mastershot in...

This scene is done using a single sustained mastershot in order to allow the actors the most conducive environment for intimacy and intensity and in order to best communicate what happens in the film's pivotal scene. It cannot be cut without compromising the central scene of the narrative and thus rendering the mystery of the film incomprehensible. It remains more than a bit absurd to me that this scene would garner an R if shot exactly the same but from just the torso up but becomes an NC-17 because the mastershot reveals full bodies.