I was there just last week. The tour is very short, but they added an exhibit featuring their cleanly-cut washed history and a short bible exhibit that shows the name Jehovah in the bible, even including it in the new testament. I asked the tour guide if any reason was given for leaving brooklyn. He said that no official reason has been given, except the Governing Body has hinted things here and there like corruption of the city, homosexuality, and saying it would be better for the evangelising work (not sure how exactly but I didn't question further). He also said that selling the properties would bring in money but that it wasn't the reason why they are moving. The tour guide was a new guy so I don't expect him to know too much but that's all I can inform.
All other buildings will be sold off, and that one featured in the video will be last to go.