The Windows 10 Anniversary Update, due this summer, will expand the range of video and audio codecs that are supported by the Edge browser. Microsoft is adding the VP9 video codec, the Opus audio codec, and the WebM container format.
VP9 and WebM are both spearheaded by Google. Google bought video codec company On2 in 2010 with the intent of opening up On2's VP8 codec to serve as an open source, royalty-free alternative to the open but royalty-incurring H.264. Unfortunately, groups claiming to have patents that covered VP8 emerged. Google ultimately came to an agreement with those groups in 2013 to ensure the codec's royalty-free status, but by then, H.264 was too firmly entrenched to displace.
VP9 is a successor to VP8 that is more efficient and essential for the growing demand for 4K video. Along with Microsoft and others, Google has joined the Alliance for Open Media to promote VP9's development and try to ensure that it remains royalty-free. As with VP8 before it, VP9 is covered by patents, but the companies hope that they own all the relevant patents and hence are in a position to grant a royalty-free license. Microsoft announced in September 2015 that it was starting work on VP9 for Edge.