These guys have a whole string of videos...they're not scientists by any means. At least not that I know of! They are just getting their 15 min. of online video fame using their same ole tired out set over and over...
Genetics affects us, of course. Does that mean that we should not exercise? Of course not.
Does it mean that we will have the same effect necessarily as someone else with a completely different body? Again, of course not.
Their point is well-taken that there are so many ads out there for devices.
I'm sure that a lot of them work for different people. As long as people get moving, get fit, and get firm, so what! At least it's not pills or surgery.