When I was at Oxford for my interview at the Ruskin school I spoke very concisely about my works and goals and answered questions as straightforward as possible. My biggest fault was not bringing any new things to show for in my portfolio. Everyone else had done so, even unfinished works, but aside from that most people babbled and as far as I'm aware they all got in. These professors are artists themselves, they've been dealing with young artists that merit in creativity more than eloquent speech for years. They expect babbling so it's not the worst thing in the world, especially if the conversation has flow. That means that you hopefully found an interesting topic that they wanted you to expand on. As long as it showed your potential for creativity and hopefully some critical thinking, that's usually what they want. Talking about meaning behind your own art is what they expect from you, if they think you're going off track they would try to steer you back on to it, it's important to be attentive and listen but there is no harm in showing them you're passionate.Also try to remember these professors have been doing interviews for years and so it's important to consider that they do have a checklist to get through, but they also like to be amused. If you're boring, which I'm sure I was, they won't see why you're qualified to enrich their university environment. They take your anxiety into consideration, they know full well how nervous you are especially if you're still in high school or if it's your first time applying.