Those building brushes are made by me.
All brushes are saved in high resoultion, so you can brush your buildings and build your city or anything your imagination comes with, no matter how big your document is.
I created those building brushes by a simple use of the lasso tool, and a lot of straight lines (you know, with the shift key).
You can see here an example of using those brushes (see the buildings at the background).
In addition, you will see that the brushes comes with some Photoshop settings like Other Dynamics (work for those who have a tablet),
Shape Dynamics and Scattering. (Later on I will make a video explaining anything about those settings).