Well, again, they're captured from his hand, so he'd know which two were taken (or should unless he's paying absolutely zero attention to the cards he's drawn).
As for once the cards are captured, the rules do specify that:
when a card effect instructs the LS player
to rescue a captured card, he chooses a DS objective,
then randomly selects one captured card at that
objective and returns the rescued card to his hand. (p. 26)
That "randomly" would seem to imply that he couldn't look at the captured cards while they're captured. Of course, that would really only come into play if you had multiple captured cards at a single location, since there's nothing really random about choosing from one card, and one would hope he was aware of what that captured card was.