Sorry, but that's a silly thought. It was caught by many as soon as it happened, as part of his campaign event. Watch the video full screen, he's mumbling along a lot right before hand, but when he says it he's looking straight into the camera and you can easily read his lips.
And this is actually newsworthy, as it shows he can't control his thoughts, or speech, at best. At worst, he's admitting to fraud, accidentally. More than a blunder, when you're running for President in a hotly contested election.
No I just meant if it is a deep fake video that would not be good to pass it around. I would have it authenticated if I could because if it is fake the Trump campaign will get reamed.
I did watch the full video and look around his mouth on either side when he is talking.