I also experienced a room filled with silence that was only haltingly broken by a few sharply pressed keys. However when I enthusiastically asked more questions and acted like I was having fun the interviewer opened up quite a bit more. The interviewer got up from across the table and helped clarify a point they were making on the white board. The conversation eventually got to the point where it felt something like that linked video, but boy did I have to dance for that.

My experience was that the video might show the ideal interview but not the default one. The default was tense silence and "okays" that barely restrained their judgement. The linked video seems to give an entertainingly wrong impression.