They were "tightlipped" (sorry couldnt resist) But they are not about to talk especially on TV, they clammed up better than Joran did. They know more but are trying to not let their parents know what really happened, and/or have been advised to say nothing.
I can just see it now....ques: did you drink , do drugs, flirt, dance while at C&C? answer: absolutely not we went there to have a bite to eat and than we left, ques: did you see Natalee? answer: yes we are absolute the bestest of friends I mean just the best, we briefly saw her for a minute,ques: if you are such great friends why didnt you make certain Natalee left with you? answer: have no answer for that one, grit teeth, clench teeth etc.
Thats my version of how the questioning would probably go now. Looks like they have been advised to say NOTHING.