Yeah, famous/well known youtubers can be a hot topic, it seems. I do have quite a few of youtubers that I highly dislike (I will not name any, as it is my own personal opinion, don't want to start a war here either) but the best thing to do in such cases, if I do stumble upon with a video or topic that surprised me in a bad way, I hit that dislike button and carry on with my life. I avoid then watching topics from that person on which I don't agree on. If it is put in the video, I skip the part of self promotion (not like I'd ever be able to order from US or afford it in that matter).
If you disagree with the youtuber, any reaction (even bad one) and comments can actually help them out (now that I think of it, should I keep giving those thumbs down if I disagree or don't like smth?). There's not going to be a single person that I agree with 100% and that is okay. In the world of "fame" I am so used seeing and hearing self promotion. To be fair, this persistence is what helps with their own success or their aims. Or even just to pay their bills.
I like to hear all sides and kind of filter out the good from bad. The bad stuff (lets say the self promotion and the ekkie diet) which is not backed up by any studies or anything, I will ignore. Or, if it intrigues me, I will go on a deep search of the topic until I get a Phd and a Nobel prize for it (that's a joke, but you get my jest). Because maybe I was wrong. I remember back then I would FIGHT people for suggesting to give Apple cider vinegar to birds with yeast in crop. Until our vet suggested the same to our little sick budgie. And since then I make sure to read some claims, posts or even scientific papers on some matter. (I was always like "fite me >:V " and I am not proud of it)
My suggestion is to shrug it off, and instead of fighting with people to just say "I disagree" and try to back up your reason if you're asked for it. If people press, often nothing will change their minds. We also have to accept that there are people who take Jamie's suggestions and words as the one and only, and they might stick to that. While we all can express our opinions but when disagreeing it's best to do it with respect. Instead of sticking to the anger what this youtuber said, best to carry on with the research, or even just have a chat with a reputable avian vet on the matter if you have any doubts. Keep in mind even on this forum you will find people with whom you don't seem to agree, despite them being experienced with birds of specific species you're researching on. I can bet many people are rolling their eyes on my posts and quietly disagreeing with me, hahaha. It's like with Parenting, how to raise up children, hahah...
Sorry for the wall of scrambled text, It's super hard for me to collect my mind into making sensible text :')