This is definitely the most on-topic question anyways. The weird thing is that it seems like there is 0 actual copyright case against the subreddit moderators, who seem to have nothing to do with the 3 streamers who made the reaction videos.
I am not a lawyer, but I would hope there is not a law saying people cannot share a link to potentially copyright infringing content, which is hosted on a different platform, and posted by somebody else entirely 