It's obviously more complex than that video. It's to do with the differentiation between primary and secondary hypogonadism. If you have low T and high FSH and LH it is primary and means your testes are not working correctly (it's more nuanced than this because I have high FSH but in range LH and still primary unless I go to a GP in which case they say I'm totally fine anyway).
If you have low T and low FSH and LH then it is secondary and HCG may work to restart the hpta axis. This could be a number of different things, but yes brain, or previous anabolics, or opioids etc etc.
I would be surprised if your provider didn't measure those hormones initially, and if they did they wouldn't tell you to try HCG first because it probably won't work. Attia was probably on stuff before.