It is interesting to note that the website that is being referred to here provides for "academic" instruction only. As it turns out, a novice diver's instruction in scuba is only as good as his/her instructor. The level of instruction that the diver gets has more to do with the instructors competance in teaching the material and the students interest in learning than the source of the material. Scuba diving has more to do with the body learning large motor skills, and reliably reacting with specific responses to diving situations that assures the divers safety.
True, a diver needs to intellectually understand what physically and physiologically happens in the marine environment, but where and when this intellectual understanding is achieved is mostly irrelevant to the learning process. The scuba student's instructor must assure that both the academic part of scuba instruction has been "learned and internalized" as well as the motor skills mastered prior to certification being conferred.
Because of this, mail order certification can never happen. Large motor skills can only be learned through demonstration , imitation, and repetition. In today's fast paced world, we will continue to see experiements in the ways that the intellectual understanding of the concepts encountered while diving can be accomplished. Some of the educational methods of the future may actually be beneficial to sport diving.
I do not know, or am I aware of the methodology that this website uses in their attempt to educate. I do, however, believe that we will see more and more innovation in scuba education from other sources, including our revered scuba training agencies.
Good diving to you all.