What do you think of me telling someone how awful their YouTube channel is?
What would you tell them is awful about their youtube channel?
They're playing the victim six ways from Thursday.
You shouldn't be rude to someone when it comes to their work. Especially if you don't have an urgent need to do so. If you don't like someone's content anymore then its best just to move on quietly.
Don't I have the right to comment their video? What's the difference from a public Youtube comment?
You should provide positive comments on someone's channel. Do not go out of your way to hurt someone's feelings just because you don't agree with their comment. Instead, simply watch a different channel.