The betrayal that she's portraying here is the betrayal of Mary Magdalene. She was one of Jesus' foremost apostles but instead has been portrayed as a prostitue and not very important character in Jesus' story. Hence the symbolism in the video of the wave crashing on her and the line "Ive learned love is like a brick/you can build a house or sink a dead body." In the video when she sings this line she first pats Peter on the shoulder (Peter is the "rock" that the house of the "Church" was built on) then gestures towards herself, Mary Magdalene, an influential woman that was sunk in history. Religions are made by man, not god. I love this video/song for bringing up these issues of history, destiny, forgiveness, and the roles/status of women in ancient history and the present.