British, not a teacher
They mean that the whole program (US) / programme (UK) was an hour-long feature, the content of which was all about the deceased ex-presenter of Meet the Press. They kept his old seat empty as a mark of respect. Flying a flag at half-staff (US) / half-mast (UK) is also a mark of respect used when someone dies.
By the way, I'm not sure what you mean by 'overstriking'. Do you mean "the words above"