The title is an overstatement of what, per se?

I thought this was interesting:

http://www.koyaanisqatsi.org/films/evidence.php

Well, the first question it makes you ask is: evidence of what? And, for any good answer to this question, the evidence is minor -- but a single experiment with one set of subjects.

Then there's this quote in the link you gave: "The phenomenon recorded in Evidence relates not to programming or software, but to the medium itself - television the household appliance, the cathode ray tube, the radiation gun aimed at the viewer."

Yet, the short depicts their (edited) response to Dumbo, only.

What could have made this short more interesting? A comparison scene of the kids reacting to something different, perhaps a teacher reading them a story, or a Sunday school lecture.

I think you could be asking too much of a short film, Monk. That is not to say that an extended comparison piece would not also be interesting--I think I'd very much like to see that done. Have at it. But Reggio just filmed eight minutes or so of kids watching Dumbo.

The title is provocative. What is it evidence of? Who can say for sure? But evidence it is. You say that the evidence is minor. That seems to me a secondary question. The evidence is the film; the weight we give to that evidence is subjective. I think I'd have a different reaction if the title were "Proof" than I do with the more modest title "Evidence."