The comparison of a magician to a surgeon and painter to a cameraman was creative and somewhat unexpected. It helps to reinforce Benjamin's argument about a painter and a cameraman. Everyone follows a procedure, but a cameraman is able to create his art with a special procedure of similar shots, like a magician. While the painter must follow a natural distance from reality analogous to the surgeon.
How is it possible for him to lose the aura instead of it changing? Is it because the actor is taking the role of another person that "the aura that envelops the actor vanishes, and with it the aura of the figure he portrays."? How is this different than the man being at different locations (the actor's setting) and still being the same person (even though he is acting)?