Unfortunately this just adds to the total mangling of the phrase HIIT. This definition of HIIT used by the study is absurd given that HIIT derived from Tabata. It's well know that high intensity training burns more fat than lower intensity - it just burns a lower percentage per unit of energy consumed - but it burns in total a lot more energy for the same period.

From the study: "High Intensity Interval Training workouts generally last around 30-40 minutes although they can be a bit shorter. The “high-intensity intervals” are typically in the 2-4 minute range. "