That isnt on the blockchain. The blockchain only takes text. Anything loaded to Steemit like pics goes to an Amazon Web Server and DTube has a server company.
They can take that kind of stuff down.
It is only text that is in the blockchain meaning that it requires the 21 witnesses to agree to remove it.
mmmmm, I had not caught that. I always had that doubt about it, now that you say it is pretty obvious.