While some YouTubers may be correct about the things they talk about, or may even be doctors or researchers, I think we're in a pretty sus world if disputes about factual or even anecdotal information can come down to whether someone's watching and getting recommended the same content on a video site designed to exploit chronic viewing habits.
If your crowd does differently, just cite that, if they don't, speak from a place of speculation if that's what you'd like like them to do, because that's basically what watching YouTube does for a person.
But yes, he is also popular on youtube.
I also like a bunch of other channels and have derived what feels like good information from them, I'd recommend them on that basis to people I felt would find it useful or entertaining. Just because I wouldn't cite them as an authoritative source doesn't mean it's a strike against them, it just means I don't think it's fair to tell someone they're wrong because my favorite YouTuber, even if they seem credible, well-natured, and are worth recommending, says X.
There are plenty out there doing good by their viewers and I love that, especially Canadian ones, but it's insufficient for being hyperbolic, imo, about what's impossible to make a claim about, and I don't think arguments from apparent authority are to be encouraged anyway.
In some cases, I've checked the advice of other MD content producers against real practitioners, and they've gave me the thumbs up in terms of credibility, and that obviously changes the vibe a bit, but still I'd hesitate to go too far with that, there's a lot people will do for money and attention.