videos can be altered in this way for a long long time now. just not by neural networks. so in reality, it changes nothing.
As the technology improves and becomes accessible soon anybody will be able to edit videos convincingly without having to invest a massive amount of time or money. That's going to have a large impact I think.
So in that sense it could have still be done pretty cheap.
A better example would probably be the moon landing footage or 9/11. And then it's really only questioned by conspiracy theorists and specifically because a state actor might have wanted to hide the evidence of a conspiracy.
Tomorrow with this new technology I might not convince you that Bigfoot exists but I might be able to show you extremely convincing footage of Margaret Thatcher and Mao Zedong frolicking in the Swiss Alps while Tupac is watching.
I had no idea Mao and Tupac were friends.