She clearly demonstrated the importance of darker tones to provide contrast to bring light into a watercolour painting. I always think interiors present a challenge because you have to indicate space where you effectively have only fore and middle ground and nothing distant. Her reference photo had the light coming through a window facing the viewer so there was really nothing much of the outside to be seen. She suggested using a photo editing package to manipulate the light in photos as otherwise some of the information is not visible.
To see more of her work visit her website http://www.sareenarts.com/
Here are some more images from her demonstration