What's remarkable about the following video is that Jacob Collier sings the correct note and plays the piano note, which is 14 cents out of tune by design — and you can just hear how out of tune it is!
Fascinating indeed. 
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Beach L168, Wish, baCh, WOW Petrof, Fake Steinway, VS
TIME
I haven't a clue what this guy is on about. What's he trying to demonstrate, that 3rds and 5ths aren't pure if the piano is tuned in an equal temperament. The whole world knows that already.
If he wants perfect 3rds and 5ths for his C chord then just tune the thing in an appropriate non equal temperament.
Sydney Australia
Retired part-time piano technician
navindra But being theoretically "out of tune" by the amount he describes has worked fine for piano music for over 200 years although composer Michael Harrison doesn't think so. I saw him several decades ago play his special piano at Faust Harrison Pianos in New York City. If I remember correctly, and I'm not sure about this, he had the special rods he could insert into a piano tuned the normal way that allowed the piano to produce the theoretically correct notes in different keys. If you Google Michael Harrison you can read articles about his specially prepared pianos and listen to his music.
JohnCW Yeah, he probably discovered this all on his own organically, so it feels like a revelation.
So here he plays a 1st and 5th while singing a perfect 3rd, once he plays the 3rd on the piano, it sounds pretty bad with his voice. As a singer with an excellent sense of pitch, I imagine this can be infuriating!
Usually it's the other way around, the instrumentalists complaining about singers never being on pitch. 
pianoloverus I saw him several decades ago play his special piano at Faust Harrison Pianos in New York City. If I remember correctly, and I'm not sure about this, he had the special rods he could insert into a piano tuned the normal way that allowed the piano to produce the theoretically correct notes in different keys.
That's very informative and fascinating, thank you! I'll look this up!
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Beach L168, Wish, baCh, WOW Petrof, Fake Steinway, VS
TIME
JohnCW The whole world knows that already.
Most people don't. In a forum for tuners and technicians, of course you do.
keystring I think most non musicians don't understand the compromises made when tuning the piano but my guess is a reasonable percentage of pianists, singers, string players, etc. are aware of this.
pianoloverus I think most non musicians don't understand the compromises made when tuning the piano but my guess is a reasonable percentage of pianists, singers, string players, etc. are aware of this.
String players probably, singers maybe, pianists I'm not so sure. Maybe intellectually (if at all) but it's not something you learn to listen for. When I went from several years of violin lessons back to piano, I had to turn off my ear to some degree because I was literally bothered by what I heard.
And this guy explained the temperament quite well that even I can understand.
