Up until now the only way to view 360 degree videos and photos in Windows Mixed Reality from the sites like Youtube was an expensive 3rd party app from Cyberlink. That has changed with Microsoft’s new extension for Microsoft Edge.
The 360 viewer extension enables you to watch 360 degree videos on YouTube, Facebook, Twitter and the NYTimes directly from the Cliff House in Windows Mixed Reality. It adds an icon to the video view in Microsoft Edge that enables immersive mode.
You can find the extension in the Microsoft Store
With the 360 Viewer Edge extension, you can view 360 videos and photos from many popular websites on your Windows Mixed Reality headset. Launch the 360 video from your Edge window on your PC, click on the Mixed Reality icon in the lower right corner, and see the video or photo in your Mixed Reality headset that you have plugged in your PC. Currently supported content from these websites: YouTube, Facebook, Twitter, and NYTimes. Websites that embed content from YouTube also work.