A great video. Thanks for posting. I don't believe the Apple has a GPS, right? If so, I wish they had pointed that out.
Also, as I understand it, on a treadmill, measuring distance is dependent on an accurate calibration of stride length. I haven't looked at their supporting video on "How we tested," so hopefully it is answered there, and it was done fairly.
Running outdoors, seems to me, nothing beats an accurate GPS track.