Metalepsis — met-uh-LEP-sis. In narratology, a crossing between levels of a story that ordinarily remain separate: a narrator entering the world being narrated, for example. In rhetoric, the word can also describe a reference reached through a chain of related figures. Living Handbook of Narratology; Oxford Classical Dictionary.
“When the off-screen narrator enters the dramatized story and starts answering its characters, the film creates a metalepsis.” That sentence names a genuine level crossing rather than an ordinary documentary appearance.