This is the Start of the Music Video Which is filmed in front of a house as it represents a solemn feel to the music video.
1st Scene This is where you can see the back of Katie sitting on a bench in front of a road- this represents how she is feeling hopeless.
2nd Scene- In this scene Katie sits with her arms crossed, facing away from the camera as she is clearly fed up of her emotions whcih are slowly overtaking her.
3rd Scene- This is where Katie is sitting on the curb with her hands in front of her face, and this person in her mind keeps appearing, which is making her feel heavy.
4th scene-This is where you can see Katie- while you see her face, she is showing intense emotion as she is looking hopelessly away from the camera.
Final scene-You can see that again Katie is sitting on the curb with her hands in front of her face because the line repeats" You're in my head" which expresses the intense emotion of the person who constantly comes to mind in the song.