After installing KB3011970 from Microsoft maintenance on 12-09-2014, every streaming service which used digital rights failed under windows 7 (ultimate). This is true when using FireFox or IE11 or any other browser that utilizes Silverlight. This occurred on three of my computers prior to discovering the failure. I stopped and investigated.
KB3011970 apparently installed version 5.1.31010.0 and stores the HDS data in directory program data\playreadysilverlight. Previous versions utilized the directory program data\playready. Testing with Amazon, Netflix and other streaming services showed a disconnect in the code. The services could not reconcile the digital rights. Error codes are specific to the streaming site but include 6001 for amazon and N8152 for Netflix.
Programs which I deployed which use silverfast also fail with digital rights because of the change in KB3011970.
After chasing the problem for many hours and talking to Microsoft (who wanted to charge for figuring out their problem), tweaking the registry and directories, uninstalling and reinstalling various components the only solution at this point is to uninstall KB3011970 or manually uninstall Silverlight and install version V5.1.30514.0
If anyone else has a suggestion, I will be happy to test.