Here's another screencast I've recorded which shows how to apply the sample custom master pages available on Office Online to Windows SharePoint Services team sites.
This recording is based on the Demo Showcase virtual images, a resource readily available to Microsoft Gold and Certified partners. Total running time is just over two and a half minutes :)
Cool stuff Chris! The Demoshowcase VMs are also available to SBSC Partners, they were in the last SBSC Toolkit as part of MAPS.