I just saw this documentary yesterday of Gerhard Richter, the very famous Cologne, Germany artist. It was a very good look at the man, his latest methods and the inside game at the very highest levels of the art world. I hope you get to see it. Click on the link to see a preview from the full-length documentary film.
What you are seeing here is a very large squeegee loaded with green paint being drawn across this large canvas, completely remaking its appearance.