I find that rather difficult to believe. e.g. If you consider the heart-rate. 1 minute of say 180bpm just isn't going to equal 45 minutes of 150bpm. I'm sure it does scale to some extent but not that dramatically...
Such experiments essentially make a point that the main results of training sessions occur not because of the direct action on muscles and calorie burn during the exercise but rather because of some changes in body self-regulation that are triggered by the training session but act throughout the rest of the day/week.
If that 1 minute of 180bpm causes an upregulation of +1bpm (or an increase of base metabolism for calorie burn) for the whole next week in a way that moderate exercise doesn't, then it can quite plausibly have significant effects..
150 bpm is usually considered a vigorous workout (modulo variance in age/ability/genetics) and depending on many factors could be very hard to maintain for 45 minutes.
If that 1 minute of 180bpm causes an upregulation of +1bpm (or an increase of base metabolism for calorie burn) for the whole next week in a way that moderate exercise doesn't, then it can quite plausibly have significant effects..