I wondered how people could miss Sergey's point. Looking down at your phone breaks eye contact, and puts you in a subservient (bowing) position.
Not to mention the reverse: with video, all of a sudden, I have to care how I look, what I'm wearing, what's visible in the background, etc. Gah, what a pain.
So while there are definitely positive aspects to video calls, and it's great that they're an option, no way should they be the default, either technically (the default state of the app) or "societally" (i.e., what people expect, with audio-only being taken as a sign of something suspicious).
One reason I don't use Google hangouts more often is simply that: it defaults to video, and requires specific action to turn that off. Don't do that shit.
I'm not saying definitively that it's pseudo-science, but it does quack a lot like it.