The spam filter might be picking up the comment. Then it will require approval from the creator of the video. This filter is incredibly aggressive, because of just how much garbage is spammed.

As an example, YouTube hid this comment and tagged it as "likely spam":

>I saw a Jean Bart video and I thought I might be in it as I went up against you yesterday, glad I was not in the other team in this one lol

However, there also exists some kind of other system that sometimes removes comments. I'm not sure how that one works. Even as the creator of the video I've had my comments disappear, but that might've also just been a bug.

I tried to have fun with comment filter to figure out what causes comments to trigger it but it seem it is implemented so that when you get couple comments removed you are no longer able to put any comment, they are just going to vanish whatever you write.

It was me. I often spend 10 minutes writing a comment, I post it and sooner than later I delete it.

Effort to put my thoughts into coherent words is often more important to me than the comment itself, and thus it had had served it's purpose in the instant I wrote it down.

I am also doing that frequently.

I spend a bunch of time writing comment only to find out it does not improve the discussion one iota, so I delete it.

But having an occasion to think something through lets me organize my thoughts a tiny bit better.

I don't comment in the comment section either, but I sometimes read it and I often see people accusing the channel of deleting comments, and the responses from the channel owners that they don't delete any comments. And these channels don't even have anything to do with politics or any controversial topics.

I sometimes comment in the live chat on livestreams though. I'm sure there is some kind of super clever and sophisticated algorithm to filter out comments, but in practice as far as I can tell, what comment in the live chat gets through is virtually just random.

I believe channel owners. The comments are being removed so regularly that would be practically impossible for somebody to react so perfectly within 2-3s of every comment.

It is just youtube trying to create illusion of functioning community by automatically censoring anything and anybody that can even potentially be negative, divisive or controversial.

And we know the dangers of removing every critical opinion...

Absolutely, in the full context channel owners often have zero incentive to remove any comments and it makes zero sense for them to do so, so I believe them too. Most people are aware of what YouTube is doing by now, but once in a while you have someone who will blame it on the channel.