Seelenprobe means “examination of the soul”.
Our soul can only be challenged and temped, as HE said, by making a decision. In his own words: “Die Seele kann nur in der Entscheidung versucht und erprobt werden.”
Ophelia Haneke had to prove, that she literally would do everything, he would ask her to do.
She had to descend from her high horse and (klaftertief durch schlamm waten).
The plan for the examination (der Seelenprobe) occured between the second and the third day of shooting. Actually HE kept asking different people, if they would have a camera with night-shot. This was the moment, where Marie-Christine lost her trust in HIM. She told me (Malaria), about this and I was quiet thrilled and exited.
On the [third day of shooting] HE literally demanded from Ophelia to make a sacrifice, to do the almost impossible.
To see, what this actually was and what he did with her, go here. For this you must be [loged in].