Per a recent update to Microsoft's Deprecated Windows features page, Legacy DRM services utilized by Windows Media Player and Silverlight clients for Windows 7 and Windows 8 are now deprecated. This will prevent the streaming or playback of DRM-protected content in those applications on those operating systems. It also includes playing content from personal CD rips and streaming from a Silverlight or Windows 8 client to an Xbox 360 if you were still doing that.
For those unfamiliar, "DRM" refers to Digital Rights Management. Basically, DRM tech ensures that you aren't stealing or playing back pirated content. Of course, piracy still exists, but these days, most officially distributed movies, TV shows, games, etc., all involve some form of DRM unless explicitly advertised as DRM-free.
DRM does seem like harmless piracy prevention on paper. Still, it hasn't been all that effective at eliminating piracy— and where it is implemented, it mainly punishes or inconveniences paying customers. It is an excellent example of DRM's folly. Now, anyone who had previously opted into Microsoft's legitimate media streaming ecosystem with Windows 7 and 8 is being penalized for buying media legitimately since it will no longer work without them being forced to pivot to other streaming solutions.
The loss of Legacy DRM services is only the most recent deprecation on Microsoft's chopping block. Paint 3D is set to get a permanent axing in November, and somewhat frighteningly, even Control Panel seemed to be in the crosshairs for a little while there. Fortunately, Control Panel is safe for now— but seeing basic Windows Media Player functionality being killed off for older versions of Windows leaves an unmistakably bitter taste in the mouth. If Microsoft fancies itself a media company, it must keep legitimate media playable in its purchased software.