I remember when I first started interviewing people on camera, I wrote lots of interview questions based on what was needed for the video. I soon realised that I was missing the point. This style of Q & A response almost reinforces that it is not a natural conversation and can result in a very unnatural interview.
Discussion promotes far richer and more relevant interview footage. By engaging someone in a discussion it really helps people focus their attention on the conversation. This is one of the challenges of interviews I really enjoy. This is a good example of the result of a good discussion.