Complex sentence: She again looks at the silhouettes in the window of the building, as it collapses on her, once again changing the scene, this time the singer looking through another window, and turns around to a mirror which captures a door.
Split into simpler sentences: She again looks at the silhouettes in the window of the building, as it collapses on her, once again changing the scene. This time, the singer is looking through another window, and then turns around to a mirror which captures a door.