Talk show hosts typically have a meeting with their guests before the show starts. So its not outside the realm of possibility.
but it is probably more likely that this scene is just oprah hanging out after the interview and they just kept the cameras rolling for extra footage.
And Joe is the controlling type and the type that likes to have attention on him, so no doubt he's going to hover around wherever oprah and the cameras are, if he can.
And even though a lot of talk shows make the producer or interns do pre-interviews, I believe that Oprah is so adamant about running her own show that she would want to have a hand in everything she can. Plus, it's the Jackson family, she probably wanted to just spend time with them because she can.
And like someone else said, even interviews that seem spontaneous are usually rehearsed or mapped out before the cameras roll.
I'm willing to put money on the fact that Oprah met the whole family when she arrived at the house.
