Microsoft announced on its blog that it will only support H264. As a consequence it does not support video as provided by the projects of the Wikimedia Foundation notably Wikipedia.
Video is technically about to get to the stage for Wikipedia where it will become more and more visible. There are contacts with GLAM that will provide us with relevant material, material that will not be provided in H264.
So there is this stand off not unlike the Apple and Adobe situation. The difference is that Microsoft has no control over the platform. In Europe Microsoft has to offer the choice of an alternative browser. It is quite easy to bypass IE elsewhere as well.
Given that Facebook is to provide Wikipedia content, two of the most popular websites will be suboptimal supported by the "new, mega, wonderful (insert your marketing adjective)" offering of Microsoft. As you are the customer and as you can, you can vote with your feet.