The OBS Studio software aids players in screen capturing and live-streaming gameplay of their favorite titles.

As pointed out in the latest Windows 11 Version 24H2 update post, OS build 26100.4946 (which launched on August 12) has ...

You can then use it with streaming software, like OBS, so you can overlay your face on your video stream.

OBS, the streaming software, sees that mirrored screen on your computer and uses it as a source for your stream, like a camera. So, people watching your stream, see what's happening on your phone!