Moving to HTML5 Premium Media | Microsoft Edge Dev Blog

Also see Microsoft: Stop using Microsoft Silverlight. (Everyone else has) (The Register)

"The commercial media industry is undergoing a major transition as content providers move away from proprietary web plug-in based delivery mechanisms (such as Flash or Silverlight), and replace them with unified plug-in free video players that are based on HTML5 specifications and commercial media encoding capabilities.  Browsers are moving away from plug-ins as well, as Chrome is with NPAPI and Microsoft Edge is with ActiveX, and toward more secure extension models."

Moving to HTML5 Premium Media | Microsoft Edge Dev Blog