I have owned dozens of sound systems, none of which claimed to cover X number of square feet. They all, however, provided diagrams of their coverage.
My friend, Graham, is correct in that conventional speakers project sound directly in front of them, usually in a cone area of about 45 degrees. However, it appears as if Yamaha is not using conventional speaker cones, but instead, something entirely different is shape, design and material - similar to the Bose line array system speakers. From the above dispersion diagram, they do appear to have some forward projection, and even a bit of projection to the sides. This would be impossible with conventional speakers and materials.
I guess we'll soon find out when we get more information from users on this and other sites.
Good luck,
Gary