That's the part that really struck me. I thought it was particularly impressive with the Sal Khan maths tutor demo and the one with BeMyEyes. The comment at the end about the dog was an interesting ad-lib.

The only slightly annoying thing at the moment is they seem hard to interrupt, which is an important mechanism in conversations. But that seems like a solvable problem. They kind of need to be able to interpret body language a bit to spot when the speaker is about to interrupt.