I did the tour in October. You have the option to stay in the Magic Kingdom after the 3:00 Parade which is the last thing on the tour, but they still will scan your ticket,, or you can ride back to Epcot and the tour finishes at 4:00 p.m. in the Bus Terminal Parking lot.
On the podcast, they were talking about the tour and the fact that they did not tour the Christmas warehouse. I was told in October, that from October 1 - end of January/early February, they do not tour the Christmas warehouse on the Backstage Magic tour, as the warehouse is empty, thus there is nothing to see there. In October, they begin loading Semi Trucks with the decorations to stage out to the various locations on property and the cruise ships, then in January/Feb they are unloading those trucks back into the warehouse. I was disappointed that this area was not on my tour, as it was one of the area's I really wanted to see.