Ken gives us a good one, in this early (Aug 12) piece on the lesson of Google shutting down video purchases.
See, after Google takes its video store down, its Internet-based DRM system will no longer function. This means that customers who have built video collections with Google Video offerings will find that their purchases no longer work. This is one of the major flaws in any DRM system based on secrets and centralized authorities: when these DRM data warehouses shut down, the DRM stops working, and consumers are left with useless junk.