You probably posted a link. From what i know YT automatically removes comments with links pointing to other sites (not itself), it's not related to your chain of comments or CiG or any conspiracy...
Nope, on the first there was no link. On later tests there was one link to another youtube video. Other tests also vanished into the ether.
Thing is, i did some searching and i can't find any info about any block function that stops you replying to someone like this. It was bizarre.