Yeah I don't buy this.
I've had my Mira e : S for 4 months, use only hi-octane fuel, clean and maintain vents/filters regularly, and got an average of 13.5 - 14.0 km/l in the summer months with:
gentle driving (green, "eco" dash lights all the way through)
reasonable air conditioning settings (28 C, auto)
Now I'm getting a winter average that ranges anywhere between 16.0 - 22.0 km/l, with air conditioning off (temperature set to 26 C, automatic heating in the morning). Temperature and climate conditions, fuel/air filter quality, fuel/air particulate content, driving technique, engine oil quality, engine and fuel pump health, eco-idle usage, using regenerative braking appropriately... the list of factors that come into play is sizable, and one video won't prove anything.
The OP's post reeks of spam; proof provided is insufficient to take the claim seriously.
PS: A particularly dishonest way of boosting your calculated average is to clear the gauge by holding down the stalk button and then either coast at a constant speed, or let go of the gas pedal whilst the car coasts to a stop. This will show a reading anywhere from 50.0 km/l to 99.9 km/l, simply because you're consuming only enough fuel to maintain baseline RPM, and the car is moving at a speed that cannot be reached or sustained with that kind of power output. You can see if someone's potentially done this if the average on the car's dash changes in large increments - an average figure that hasn't been messed with will show only minute variations.