Well, don't respond. When you do, you're letting them know that they are getting to you in some way.
Or if you do, at least come back with something witty, humorous or so cold it makes their comment look soft.
As for dealing with it, I'd say look at their channels, what videos they have, what they like, and what they say on other channels. You'll probably feel better after looking over how laughable these people are.
Veritas est index sui et falsi. (Truth is the criterion of itself and the false.)
Carpe diem quam minimum credula postero. (Sieze the day; trust little in tomorrow.)
