OK, to state it better, I meant that the fraction of traffic for video conferencing is likely so insignificant that you'd never notice the degradation of non-QoS traffic.
I wasn't contesting that bit.
Which makes the discussion of QoS in relation to FaceTime entirely beside the point. Not that that's your fault, but I wish people would stop defending AT&T's actions with fictional tales of QoS benefits.
AT&T is using the ability to use FaceTime on their network as a cattle prod to force people into plans that are more profitable for AT&T, pure and simple, end of story.