Some believe Hillary to be non compos mentis, and they have the analysis to prove it, see video link:
https://www.youtube.com/watch?v=OqbDBRWb63s&app=desktop
She obviously misspoke, she meant to read she would NOT increase taxes on the middle class, but the placards with the instructions to CHEER AND CLAP NOW were already up...so they cheered and clapped.
As for the nervous tics and over the top reactions, it's a lot like watching The Picture of Dorian Gray in slow motion. She's cracking up, she's melting, she's desperate, she knows what she's eventually going to look like in an orange jumpsuit.