Well it's obvious he's no scientist, lol.
He didn't even show his 'combing' technique. How do you know whether any excess tension has been applied to one of the quadrants, for instance?
In any useful experiment, you have to ensure that your test samples are identical and technique applied is EXACTLY the same for each sample otherwise how can you measure the results accurately or draw definite conclusions?
Manikin heads are made from heavily processed hair from different heads so the hair samples will never be identical. If this is your starting point, how can you draw any meaningful conclusion?
(You also need to perform the same experiment several times to collate enough quantifiable data/results.)
If I was gong to take him seriously, I would have preferred to see him collect his samples taking equal cuttings of human hair from the same head, following manufacturer's instructions exactly and then comparing the results at the end, without the addition of combing or pulling at the hair.
But I'm never going to accept anything as 'proof' from an online video experiment. That's just bonkers.
You just need to do your own tests and draw your own conclusions, if you want to check out different product lines.
That way, you can show the results to your clients and explain how you achieved them, as you would when doing any colour/bleach strand tests to aid the consultation process.