Yeah, the photos on the homepage just show a very fit, normal guy and it's true that nearly anyone can look like that. Compare it to Arnold Schwarzenegger (who later admitted to using steroids) and it's nuts.
It’s pretty much an open secret that every Hollywood actor that needs to be muscular for a role uses some kind of anabolic androgen. You see stories like “he put on 30 pounds of muscle for this role in six months” and it’s obvious what’s going on. Also the signature overdeveloped upper traps and that trenbalone “dryness.”
All that being said I’m still curious about the activity efficacy of the dynamic tension method. My understanding is that you basically flex to make your opposing muscle groups work against each other as a training stimulus.
Dynamic tension is almost like isometrics, except with an isometric hold you don't move the limbs and thus only hit the muscle at one angle. This is OK because muscles get stronger such that they have more strength 30 degrees each way from where you place them under stress.
The simplest way to demonstrate DT for yourself is to straighten your arms, cup your fingers together and pull the arms/shoulders outwards; then, move your straightened arms in an arc from waist to above your head. You should feel it in your shoulders and back.