Swift she was "ripping clothes off" while she went off camera during the video shoot "All modesty had to go out the window," said Swift.
The male lead in the video is Noah Mills, who is a model. "He's got incredible acting instincts," said Swift.
During the video, Swift parties in her apartment with Woodland creatures, who actually are her band members dressed in animal outfits, dancing about. "They were so mad, it was hilarious," said Swift. "It took a couple of hours, but they eventually embraced it. They were really funny in the video."
Swift she wrote the song in 30 minutes with Max Martin and Shellback, who are both from Sweden. The two have written songs for Britney Spears, Pink and Usher.
Swift will perform live on the 2012 MTV Video Music Awards at 8 p.m. eastern, Sept. 6 eastern/Pacific from Los Angeles.
The song will be on "Red," Swift's next disc, which drops in October.