I think most women her size (I'm guessing about 5'1") would probably pass right by a coat like this in a store. The fear of a coat with that much pleating and length would overwhelm their petite size would keep most from even trying it on. Next time keep this young lady in mind.
I'm sure most of you can easily see that her trick is that she has tightly wrapped the belt of the coat around her waist twice creating a cummerbund effect. This clearly defines her waist & her overall shape.