I am convinced that there are certain things that can be picked up best by listening to a real, live person.  A live teacher can do things that a video, no matter how good, just cannot do because observation affects reality. This is the fundamental principle of Quantum Theory:  Through the very act of observing, the watcher affects the outcome.  The observer changes the outcome, changes the reality.  Conscious observation creates reality.

Students in a TCI/TPRS class are not just passive, detached spectators.   It can be hard to re-train everyone involved in the classroom and convince them that students are participant observers. Teachers, students, administrators and parents all need re-training.

Electrons act differently when they are watched.  So do teachers.  In an interactive classroom, the students are affecting the outcome.  They are co-creating the lessons, the language, the tone, the meaning.

In an age of screens, this interactivity is something that we have a hard time grasping, but it is real.