Sure, the first thing is that it's not a 'proper' interview. It's assumed there is a very high chance you get an offer, they just want to make sure that you know what the course is and make sure that you do want to study it. Having said that, my interview didn't go to well, so I dunno what's going to happen. However most interviews went alright though.
They ask things like 'What do you know about the course?', 'Why this course?', 'Any plan's for the future?', and because I focused on my wanting to specialize in stats he asked 'What is Statistics?' which I had absolutely no way of explaining. Just make sure you read up on the course, that's all I can really say.
Good luck!