answer:Nothing really, it’s usually just for effect – just like the laptop itself, which is generally just a prop (I’d be willing to be half the time it’s not even turned on!). Another similar thing is how newsreaders “talk” amongst themselves or to a person off-camera after returning from an ad break (if there are any) or at the end of the programme – although it is possible they could actually be talking about something, no one seems to makes an effort to make sure this doesn’t happen (which means it’s probably for effect)