It was just really pretty demo of basically having things maxed out in Source. At the beginning they had a lighting technique that faded in and out (the light was the sun) over the water. That was pretty short. Then you go into some type of temple with pillars that are shiny. It shows the world distorted looking through a type of glass. There are some headcrabs walking around. They have another light glow effect. It's basically using every effect Source has in one scene.