Host shot addresses the audience looks at camera
interview shot doesn't look at camera, they're talking to the interviewer
BG: Don't shoot against flat surface, it should relate to story
The line is to avoid a profile shot
The host and the interview have very different roles. The host shot addresses the camera and the audience directly. The interview shot is the person addressing the interviewer, not the camera directly. The background of your interview should be related to the topic of the interview! Never use a flat surface or blank wall.