The nature of the background blurring is probably part of it, but what jumped out at me after about a minute is that the background image irregularly jiggles left and right, which was more noticable in the parts where Trickett's GF was closer in the shot. And I confirmed that the background image was jiggling by watching the image in the upper right corner, and seeing a light fixture on the wall flick back and forth. Take another look and confirm whether you see this.