A filmmaker goes undercover for decades, and actually, invents a significant method of horse and saddle measurement, that uncovers that gravity is a significant factor in the fit of the saddle. He then wrote a formula to calculate the incremental effect of the rider's weight on the three-dimensional shape of the animal's back.
By using two different measurements and a mathematical formula of the same event, a feed-back loop is created that permits the "Scientific Method" to be employed. Measure - Calibrate - Validate. Validation is the critical difference with this method.
However, the "Scientific Method", also documents that the saddle industry has been selling defective products, for decades. Regardless, he kept the cameras rolling, for decades, and thereby "got the inside scoop"...and this is the story.