I'm freaking out!!! Looks so cool!
They've already tested all the regular night mood lighting and projection lights for Hogwarts, this looks like testing for the opening, with the smoke and special lighting behind Hogwarts, etc.
Before anyone says "that means grand/soft opening is close!" or what have you, it's not out of the ordinary to test out the special "event" lighting package ahead of time, it's just programming they can save for later.
Also, they might be getting this lighting package ready for the announcement on December 8th, you never know, might be a live broadcasted announcement.