Arm flapping does not come with the latest Harry Potter game. EA producer Gary Napper told Joystiq that Harry Potter and the Deathly Hallows: Part 2 won't have any Kinect kind of functionality, though earlier titles did. EA Bright Light made a decision "early on to focus on the core of the experience, get as close to the atmosphere of the movie and make the flow of the combat feel right."
Napper put it nicely: "We didn't want to dilute any of our efforts on other things that would require a lot of the team's time to perfect."
I know you'll take this news poorly. Hang in there.