Microsoft Officially Announces VP9 Support In Edge
As of today, WebM and VP9 support is now found inside the development builds of Microsoft Edge! Microsoft describes VP9 as "an open source codec that offers efficient compression to stream HD content at lower bitrates, and is well suited to UHD streaming."
Microsoft is also said to be considering support for audio formats such as Opus. For the initial rollout, VP9 support will be concealed behind an experimental flag in Microsoft's new web browser. VP9 hardware decoding will also be exposed where supported.
More details on the VP9 support and for other open-source codecs in the future via this Windows blog post.