With voice, I am focused on what I am saying until I make my point. If it then turns out I was not listened to, that sucks and screw that person. With video, while making my point I see the person staring at the screen, eyes wandering, and I guess it's 50/50 chance they are browsing the web. They may not, but visual input makes me wonder and ruins my focus. Times that the number of participants, if everyone has video on.

And yeah, when on a call I almost always walk, helps concentration/blood flow.