着魔 Owl 

Adam Young (aka Owl City, who Taylor wrote 着魔 about) covers 着魔 and changes a few lyrics, along with a super sweet note. Listen until the end, because the last 20 秒 are just about the sweetest thing ever.
密码: 泰勒·斯威夫特, singer, owl city, adam young, 着魔, speak now, taydam