There is probably a perfectly rational explanation of this very curious and slightly unnerving video of Democratic presumptive nominee Hillary Clinton. In the absence of one, you are free to assign your own interpretation to the footage.
DaPhoneyRapperz, who posted it on YouTube, hazards a guess that Clinton is having a convulsion, adding:
It is possible she has some sort of illness, or thinks it is funny to mock people with seizures.
The reaction of the crowd suggests Clinton is trying to be funny, though the expressions on the faces of the two women at approximately the 4-second mark are looks of concern more than amusement.
It is worth recalling that Clinton sustained a concussion back in 2014, which necessitated her wearing of Coke-bottle lenses during her recuperation. At the time, Karl Rove remarked that she had suffered a “traumatic brain injury,” which Steven Galetta, a neuro-opthalmologist at NYU Langone Medical Center in New York confirmed to be true.
The going presumption ever since has been that she made a full recovery. Her behavior in this video may be totally unrelated to that injury. It would be interesting in any case to hear the Clinton campaign’s explanation.