What is the video supposed to suggest? I think it's extremely hard to conclude anything from a plot of the teacher's position over time throughout the classroom.

Is staying at the front a sign that the teacher is lazy and not helping students? Or is it that the students are competent enough without aid? That could be good if it indicates your students have been taught well enough to master the material. But it could also be bad, indicating your school does not offer enough incremental challenge, and students who are beyond their current level, but not high enough for the next level (honors or whatever), never reach their full potential.

There's far too many uncontrolled variables here. Also, it seems the wikipedia-on-ipfs page for Stigler is down.