However we managed to edit these shots to change this.
Here is the before and after:
BEFORE
AFTER
As you can see from the two images above, we completely removed the background and added brightness and contrast to make it white. To do this, we had to add image files of blank white from photoshop and add it to the video file. It was quite difficult to make sure the images weren't obvious but were blended in properly however after a few tries, we managed to do it.