Just to put this out there from the beginning, I don't know what the exact appropriate balance between censorship and freedom of expression is. Also, FB can do what they like and don't have to listen to me.
With regards to ISIS, if their recruitment videos are publicly available, then people can contest them publicly too. They can explain why this viewpoint or whatever might be appealing to certain demographics, but look at this evidence for what happens to those people once they join.
The self-harm / suicide question is harder for me. I still think it's a good idea to have this happen in the public sphere so people can expose those who encourage such things in other people. However, if an individual is being targeted specifically then maybe there should be a line there. I don't know.
As for white supremacy, yes, I said "dialogue" when what I really meant was "speech". I don't know who Richard Spencer is, but if he's blocking comments then people can still post rebuttals in other videos.
I guess my main point is that it's better to confront such things openly then to try to hide them under the rug.
There also seems to be this idea that ISIS and white supremacists and whoever can magically infect others with their dogma as a form of mind control or something. The danger, in my opinion, lies in trying to bury it. Then when people stumble upon them, or are recruited and given a login somewhere, they have access to only one side of the argument and are effectively in a bubble. In the public sphere where this plays out openly, they have ready access to conflicting information on the same platform.
I don't want a society where people aren't allowed to dislike me. I don't quite get where you're coming from. I want a society where people can say what they think and not get censored for it for the most part. It requires that we all come to terms with the fact that some people hold different opinions that we really hate.
I wasn't alive 100 to 150 years ago. However, growing up 40-ish years ago, I remember hearing such things as "I don't agree with what you say but I will defend to the death your right to say it". Not something you hear much, any more.