Yeah I heard that... however you can tell the sun and the environment he didn't let it cool all the way to the same temp.
He let it cool down a little.
This guy is an engineer, not a scientist. A scientist would have conducted two tests, in controlled environments and would have never used a IR Temp gun to take accurate measurements. He would have also been very specific about the tested areas.
Noticed how he moved the gun around until he gets a higher temp? That's not scientific.