QuoteMedia Extensions are Media Foundation components designed to extend the core Windows platform and enable Windows apps including Microsoft Edge to support an ever-increasing range of formats. Media Extensions, much like browser extensions, allow customers to extend their device beyond the core experience shipped as part of Windows 10. It also allows the developers of media technologies to update and enhance media components independently of the Windows 10 release schedule. This allows us to work with the community to deliver high quality, interoperable codecs to Edge customers quickly and reliably.
More at Introducing the Web Media Extension Package with OGG Vorbis and Theora support for Microsoft Edge - Microsoft Edge Dev BlogMicrosoft Edge Dev Blog (https://blogs.windows.com/msedgedev/2017/12/05/introducing-web-media-extension-package-ogg-vorbis-theora-support/).