If you didn't know, these guys have one of the biggest bodybuilding channels on Youtube. And they're known to spew a lot of broscience but a lot of people eat it up.
That being said, there's isn't a lot of HST material on Youtube. So to cut to the chase, they basically said:
With HST you'll probably be in the gym 1.5...2 hours a workout.
To maximize muscle, HST doesn't work. It's only good for a beginner cuz you need a lot of exercises and sets.
You put too much stress on your body with HST.
You'll be too tired to do HST often because you work all body parts.
So obviously they didn't research the program, nor do they know what they're talking about. But most people eat this **** up.
The only other review of HST I could find was this guy:
And he also canned the program without even trying it. And he's also got a big channel.
Point is, and this has probably been discussed before, but I think HST needs a Youtube presence because Youtube is massive, so you've got tons of people looking to get big and strong going to Youtube "gurus" and getting bad advice (Scooby with his "squats are bad/you can lose weight and gain muscle even after training for 30 years", etc). If HST can make a dent, hell even a small one, on the Youtube bodybuilding scene, then maybe we'll see a spike in more people using it (along with other programs that are not contradictory to HST's fundamentals like SS, Stronglifts, and DC) as opposed to doing splits with 50,000 exercises and never progressing.