To display your webcam in this browser tab, select your webcam using the drop down list. Then click on the Show Camera button. This displays a vertical cropped image to use beside or on top of slides or other content when presenting. If your webcam is in use by another app, like a meeting platform such as Zoom or Teams, turn the camera off in that app before displaying it here.
When you use the Edge browser you can detach the video using the Picture in picture option.
Links to articles/videos where you can use your webcam in a browser:
Present your slides beside your video (Windows or Mac)
Zoom multi-window sharing to share your video and slides