I think in this case it's mostly down to the fact that the robot (fore)head stays perfectly still while the human head wobbles about naturally.

It looks to me like the robot just exhibits less motion in general. This might be because (as far as I can tell) the authors optimize only to match a set of static poses, not for physical or perceptual realism of motion.

For me it's most noticeable in the lips - they just don't move as much as they should.

Especially at spots when there's a labial sound in the speech. Another phrase that comes to mind is, "gottle o' geer".

I often wonder what will happen to us, to our human psyche, to the media, when that threshold is crossed and we no longer know if an actor (in the objective sense) is human or not. It terrifies me and yet I hope I live to see it.

You'll know, because the person helping you at the store is friendly, and actually helpful.

You can't put lipstick on a paperclippy.

Today we still need human actors to portray humanoid robots in movies. Robots will be able to portray themselves long before they can portray humans.

I think this has just started to cross it. It's not perfect, but it's damn close. Of course, if they would have opened the eyes, I would likely think this was weird as hell.

I'm sure that's a valley that will be crossed in relatively short order. Whether that's a good or a bad thing is up for debate.