from the video that something bad is about to come up.
She annoys me and I think she is an idiot but I can also see that she is normally rather good as speeches. Sure they normally are rather stupid but she repeats them very well.
This one is different. I see one of two things happening. She is faking it to try and make people feel sorry for her(unlikely) or it is about to hit the fan and she is doing the smart thing and running for cover before it comes out.
Maybe I am wrong on the reasons but after only a few seconds of that video I could see something was very different.
No, I think that the reason the speech is rambling and incoherent is that she probably wrote it herself, unlike most of her other speeches.
But I do wonder if there isn't something more juicy behind the decision to quit.