I wondered if you were watching the live streaming rock1873. If so I think it could be so the producers can edit if they hear the celebs talking about someone/something that shouldn't be discussed in front of the nation. Therefore they just turn the volume off, just in case. Was interested to know where you found the live streaming as I can't find it.
Any 'reality' show has a delay in the broadcast to allow the producers to switch microphones off. This avoids any unacceptable obsceenities, or, as is more often the case, any potentially libelous statements which can be made unwittingly in conversation, but still make the programme makers potential subjects of legal action.