It still looks wrong. There's still some of the floating/stuck-on head feeling about it. Or is that just because we already know it's fake from the headline? (... and the way that the flag moves is totally wrong .../s).
You’d have to be paying real close attention to notice that, which you are primed to do because you’ve been told it’s a deep fake. You’re probably also more of an expert than most. But think of the general US electorate. How many of them, seeing this clip on the news as they prepare dinner, would know it’s fake?
The technology to fool someone who has the TV on in the background has existed forever. You could do it with a stunt double. The problem is fooling everyone such that "this video is faked" doesn't become a bigger story than the fake video in the first place.