I can take a wild guess as to the general content of Hillary's speech to a group of people willing to give a lot of money to the Democratic Party, and why she wouldn't want video/audio evidence of it:
"The Republicans are batsh[Inks] crazy, goddamn assholes. I need your money to stop them."
Anybody else want to take a stab at it?
No more likely it was along the lines of *peels off human mask, flicks lizard tongue* "Fellow reptilians! The revolution has been defeated through biased corporate illuminati media and Goldman Sachs or whatever - at last, our time is at hand!" *cackles like a woman*