I've just watched the video on a high quality monitor instead of my phone, and there is no question at all-- the background is fake, his head is stuck on top of a different body. IMO.
I'm no expert, but the outline where the body contrasts with the background is very clear.
And as pp said, if you watch the area where his neck skin joins his suit there are regular imperfections
What it all means I have no idea, but I like the idea of numerous people holding up things which terrify him, forcing him to say this. Just from a personal-to-trump point of view, not from a coercing a world leader to say what you need them to in public point of view. That's also terrifying