Heard a segment on NPR about this. The technology is very sophisticated and hard to detect. The creators of these videos can make it look absolutely real and have people saying anything they want without you being able to tell it’s faked.
We are entering a period where it will be impossible to tell real from fake in the digital media.
The President could give a national live address on TV and if someone cut into the feed they could make the President appear to say anything from declaring nuclear war to a racist rant.