Yeah, that is completely insane. I bet it would be different if he had assulted her. Hell, he probably would have had been charged as an adult, and the book thrown at him.
In fairness, if that had happened in Texas, there is a good chance (depending on area of course) that she would have been charged with all of the above and more. Sticking her hands in his mouth would have counted for two different things, because she could have had sand on her hands which means assault with a foreign abject along with sexual assault. On top of that, she could have had charges for refusing to stop once asked to. Watching that video again, I see that she also struck him with her purse (though I do not think that she ment to), and that is assault with a weapon. All charges elevated because he is a minor.
Believe it or not, we have laws in texas that contribute to higher charges for the same crime. You can get charged twice if you are protection of any sort while committing a crime. Extra if you where also armed.
Trust me, when you live in the part of Texas that Cynthia and I live in, it pays to know your local laws.