But wasn't the VT from before the day of the performance/final rehearsal - it didn't look like the studio? And why would they do a dress rehearsal somewhere else?
And if he had seen a VT in the studio as natalian suggests they can, was it a different VT to the one we saw which would have told him about Luke not doing it?
It would have been the same VT as we saw. What is going out on the TV screens to the people at home is played to the studio audience (and anyone else who is in the studio).