Apple posted this spot on September 12, 2017, the day it announced Apple Watch Series 3 and watchOS 4, and there isn't a feature demo in it. The whole pitch is Apple Watch owners reading the letters they sent Tim Cook, on camera, in their own words.
The letters that carry it are medical. One writer's car rolled over three times with the phone out of reach, and the Watch's SOS feature kept a dispatcher on the line for six minutes until help came. Another credits the Watch for the trip to the emergency room where doctors caught a condition shutting down the liver, kidneys, and heart. A parent describes a daughter newly diagnosed with Type 1 diabetes and the glucose monitor that feeds her readings to the Watch so her blood sugar can't drift dangerously low. The lighter letters are the fitness arc the Watch's marketing runs on: a writer who fell into depression at 250 pounds and now gets up at five, does pushups at five to midnight, and ran a Spartan Race in December and a marathon in February.
One line near the end, "Thank you so much for creating something that does not make me feel old," is the one the ad is built around.
The thumbnail is the ad's strongest image: a swimmer missing part of one leg, underwater, holding a letter overhead. Series 3 is the hardware behind the spot and the ad never names it. To my eye that's the template Apple's Watch keynotes have followed since, a short feature list and then the letters.
