It's identical to a clip you can find on THIS page at DB.com (scroll 'way down), except that the very beginning is different. That's new to me. Yours says that the "Ghost Host" is going to "materialize at the stroke of twelve" to act as tour guide, whereas the one at DB.com speaks of "the happy haunts" who have "donned their finest shrouds, and are prepared to greet you at the stroke of twelve." From then on the recordings are absolutely identical. What your source has given you is probably an earlier version. What I think happened is that they decided to call attention not to the recorded GH (Frees) but to the maids and butlers as the guides for the press people, so as not to create confusion. After all, the GH does NOT materialize. Pete simply rerecorded the opening few lines, and they were dubbed on to the existing recording. I wouldn't be surprised if all of this happened at the same recording session.
Anyway, it's partly unique, and it sheds light on their preparations for as smooth a press event as possible, so your wood-knocking was not in vain.