Apart from the obvious things like running order, whose turn it is to introduce what (not that any of them seem to pay a blind bit of notice to that) etc. I would imagine it's an act by act break down of what each judge needs to be saying, so they're all singing from the same hymn (script) sheet. If you watch carefully, there seem to be themes running through each act - all linked via VT, song choice, judges comments etc. That's why they all wang on about a certain act being 17 (Samantha Lavery got that from every single judge last week), sometimes its all about them being from a certain place, being an underdog, having made some sort of "transformation" etc.
Basically, instructions from producers to judges about roughly what they need to be doing at any given moment. I'd be pretty confident in saying that last weekend, rather than Sharon's papers saying "Introduce Saara Aalto (Finland)" they said something like "We don't have long term interest in Saara Alto - pretend that you barely know her name, and don't know where she is from. And REMEMBER - remind everybody that she is foreign!" Emphasized by the wide angle they used throughout the whole thing, anticipating input from the other judges. Usually, it's frame by a close up to the mentor.
If you're having trouble believing me, please offer an explaination as to how Sharon can't remember her own act's name and where they're from, but can manage to remember that Ryan Lawrie is Scottish, and Matt Terry is 23? Not even her own acts.