My guess is the combination of sort of sped-up audio and video plus lighting that is too even and "perfect", and the random blinks that don't seem to correspond

My guess is the combination of sort of sped-up audio and video plus lighting that is too even and "perfect", and the random blinks that don't seem to correspond to a regular human's average intervals (seriously, go look at it consciously, it's very weird) combine to land it straight in the uncanny valley.