Just had my interview over Skype with an adcom member. I think he got the time mixed up so it ended up being 1 hour later than what was communicated earlier, so by the time it started it was 11 PM where I was ^^; I wore a suit, but my interviewer was just wearing a sweatshirt.
The questions I got were basically why MBA, why Duke, strengths & weaknesses, and getting to know me as a person, but they were phrased differently so some of them kinda threw me off a bit. For example, he started with something like "tell me about where you are in life right now" so I answered with what I typically would with a "walk me through your resume" question. But I was mentally scrambling for a second or two there. He didn't have a question list (as far as I could tell), and made some notes.
He seemed to have a 45-min time limit because as soon as we hit the mark, he rushed to end the interview abruptly. Overall, it was more like a question & answer and less conversational than what I had expected.