This question already has an answer here:
in Reality Game Shows like Face Off, The Biggest Looser and Master Chef sometimes the contestants are commenting on what they are doing, something it's just a voice over and sometimes it's a cut away to them speaking to a camera.
How is this done? do contestants review and comment on the footage on a daily basis (ie. in one episode of Face Off the challenge can run across multiple days) or is this done post production of an episode and the post production team selects moments for the contestants to comment on?
also is there any sort of guidance to a contestant in to what to say (ie. prepared scripts)