1.- It is shows that Silvia was just simulating the blow job when it was not necessary to do it real, because it was not appearing in camera; that means that our girl is professional and very clear on what is she going to do for an scene.
2.- It is shows that the director is joking with Silvia about ending the scene with a shot direct to her eyes; she responded sarcastically "but you show me first", since is something she doesn't like. Actually in the "Behind the scenes #2" there is a moment when shes ask to her partner "no eyes please" just before the shot.
Even when the comment it was a joke, she never lose her self-confidence to stay clear on her limits.