She should tread lightly on this because it could be computer manipulated.
It seems to appear on the full length videos as well
https://www.youtube.com/watch?v=C6u1uKznCYw&feature=youtu.be&t=1140
Go to 19:20 on this video
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.