There are different kinds of seizures; some seizures are so slight that people are completely unaware of them.
The slow mo version of it reveals a lot that is not visible in the original footage. The smile dropped during the seizing, then came back right before the end, then she kind of smiled with a confused look while her head bobbed around again. Her eyes take on an unfocused, soulless look, right before she mentions the iced chai drink.
There is something seriously wrong with her. Why is she hiding from the public? Why is it that her appearances are mostly confined to scripted campaign ads, which do not feature her talking?
I’ve seen people speculating that this is a result of stress. If she loses it like this any time she gets stressed out—wouldn’t that be a really BAD quality to have in a president?