If the parent said 'oh, how frightful' and gasped, the gasp stopped the behavior. In this case, the child was shown two toys, and the speaker acted fearful toward one. The child avoided that toy and played with the other toy. The children were treating the TV as a social partner. They could generalize from a two-dimensional TV object to a real 3D object.
Kids pick up on that level of information at the end of the first year.
Again, the negative reaction from the adult elicited a stronger response from the child than did the positive reaction. Mumme said this might be something that would have offered an evolutionary advantage, that is, a child listening to a negative message would be protected from something potentially dangerous. Or, she said, because we tend to give infants more positive than negative signals, it may result in making the negative more unusual so that the infant is more likely to pay attention. It seems they've pitched it at the right level to catch the attention of young children. Even having a picture of a baby in the sky works because babies do like to see other babies and faces.