Now,getting this to work is not at all intuitive (the video makes it look SOOO easy. I spent 20 minutes trying, and finally dug around Google Earth Help until I found some directions. Here you go!
1. In the Layers section, open the "Gallery" folder, then double click on "Ancient Rome."
2. This should zoom you in, and you'll see several yellow building icons. Double click on one. This pops up a description of the building. In the lower left hand of the box, there are several links. Click on "Ancient Terrain" Wait several minutes and this will download the terrain layer into "temporary places.)
3. Once the ball stops spinning, click on a building again. In the pop up window, click on "Ancient Roman Landmarks." This will download (again with much waiting) 250 buildings.
4. If you have a REALLY fast connection and a fairly recent computer, repeat again for the "Ancient Roman Buildings--5000+)
Save the files to "My Places," but unclick them when you don't want them or they'll really slow things down.