I am not the person you are looking for necessarily... I have a 15" machine, so I cannot speak with first-hand knowledge about the nTB model. That being said, your CPU temps (both idle and when watching video) are totally normal.
This I am not sure about, but the fan may not run 100% of the time on the nTB model because of the low TDP (15 watt) CPU. I seem to recall reading somewhere that the fan on the nTB model only kicks in when necessary, so the 0 RPM at idle may be a normal finding. On the 15" both fans run at approximately 2000 RPM when at idle and speed up when necessary.