Let me quote you. You said civil.
Now while you want to argue, I should point out that you mentioned a video, which is a documented proof beyond reasonable doubt.... the mother her is more of a case of hearsay as there is no documented proof that she wanted the teen to die.
Some states also have duty laws. If you fail to help, you can be prosecuted....
That's why its easier to prove liability in civil court. It only takes 51% certainty to convict, whereas criminal is 100%.