Harry Potter TV Spot 12, the song playing.?

Hello there, I usually do not use site to ask these kind of questions, but I have no choice, since I really enjoyed this music playing. Anyhow, I was watching the Harry Potter and the Deathly Hallows Part Two, TV Spot 12. And in the background was a song playing, which really sort of made me feel cheerful. See, I'm trying to write a manuscript and music really helps me open my mind and all. I feel this song would really help to open my mind, due to the affect it had on me. So, if anyone knows what it is called I would greatly appreciate to know what the title is. Thank you very much!