It's interesting compare it to a real speech. Nixon has weird mannerisms but the deep fake feels like a disconnect between the speech and the words. It's tough to describe how my brain differentiates weird mannerisms and looking odd in a more fundamental way. In the deep fake when he reads off the names of the astronauts his shakes in this weird way that mind immediately screams that's not human, but nothing feels like that in the checkers speech.

https://www.youtube.com/watch?v=JpWwgwytdzk