Draco dies door Voldemort's hand b/c he refuses to betray his love, Hermione, and his friend, Harry. So Hermione and Harry go back in time and warn their younger selves to become his enemy so as to protect his life. Quite tragic really =(
Voldemort won the final battle against Harry, but Harry didn't get killed and decided to escape the invasion with his beloved, Hermione. (See "About This Video" section on YouTube for in-depth description.)
The song is from the kid's film, The zwaan-, zwaan Princess. The creator of this video also used Spike and Buffy as an adult Draco and Hermione. Enjoy!
