Oh look, an official announcement: http://blogs.windows.com/msedgedev/2015/09/08/announcing-vp9-support-coming-to-microsoft-edge/
In any case, welcome to the party Microsoft. Feel free to help yourself to the open bar. :-)
(And, to be fair, this isn't as fantastically unlikely as some pundits have been saying. After all, MS does own an IP stake in Opus).
