Oh my goodness I never want anyone to say they agree with something they don’t actually agree with just because they want to fit in or “be cool”…just in general let alone with me! But at the same time there is a respectful way to express the disagreement and start up a healthy discussion. I think it’s the difference between telling someone they’re wrong versus telling someone you don’t see it the same way!
I think asking questions is the best way to do it. Ask them why they think that way or if they could explain and elaborate further on the topic because who knows, said YouTuber may not have explained it brilliantly in the video or it was just a passing comment that they didn’t explain further but when they explain in more detail it’s far easier to understand why they think that way, even though you may still not totally agree. It’s also a more intelligent approach, I think. Finding out exactly why someone thinks the way they do makes for better understanding of the situation and gives you more information to decided whether you agree or not and it also creates a discussion that other people can follow and join. Rather than just outrightly deciding you disagree before having heard all of the info or all of the explanation!
But no I never want someone to just agree with me for the sake of ease but I also don’t want someone aggressively telling me how wrong I am when to could be all down to opinion! But if it’s something factual and I am wrong, I’m happy to have people respectfully tell me that and explain why and I’ll happily hold my hands up and admit I was a wally! :)