The headline sequence was recorded at 18:11, then the first item at 18:17. After the first item, it is presented live.
https://www.youtube.com/watch?v=ARmUEvhsXJo
I wouldn't be surprised if the TOTH sequence of the BBC News national bulletins are on pre-taped and then sent to live.
Sometimes on CNN (even CNNi), interview segments are taped before the programme goes on air and they insert them seamlessly in between the live segments. The only obvious clue that it was taped is when they remove the timepieces on the top of the screen.
Going back to NBC, those pre-taped segments will not matter for west coast audiences where the entire newscast airs on tape-delay anyway (save for late-breaking news after the 19.00 ET hour).