A user has provided me with screenshots of a conversation with spikestuff in a private message on discord in which he essentially bragged about intentionally flooding TASVideos Channel with re-encodes after Super Mario Bros. was published:
https://imgur.com/a/fHTf4XM
The user wishes to remain anonymous and was very hesitant to provide me with these screenshots to begin with, but I absolutely believe their validity.
EDIT: Obviously this provides no evidence that spikestuff was behind the YT comments but it pretty clearly proves that the re-encodes were done specifically in response to Super Mario Bros.
EDIT2: I find
https://i.imgur.com/kKVy2jC.png in particular to be an interesting comment because I doubt just anybody could make it. I heavily doubt regular users would know just by looking whether or not a video spammed filters. Noticing an issue with a video is one thing, but knowing the source of the issue is another entirely. The only people I could see noticing such a thing are those with encoding knowledge to begin with, which unfortunately points to publishing staff.