It looks like the vast majority is by one main user. I hadn't really noticed before as I don't spend too much time on d.tube. I'd flagged some content down to 0 rewards previously when someone uploaded Guardians of the Galaxy and I saw it come across the comics tag on Steemit.
I don't have any special connections, but I sent a report through
https://steemcleaners.org/abuse-report/

There's no centralized solution to block the account or erase the posts. A campaign of consistent flagging needs done and SteemCleaners is best equipped for that. I don't have enough Steem Power to counter this user on my own, hopefully the SteemCleaners organization will help by taking some action.