If you don't see a video image, you need to allow the browser to ask for permission to use the camera. That is in the browser settings. Then when you are asked if this page is allowed to use the camera, you need to allow it.
To make a DifRe image, tap (or click) on the video image to “snap” it. Then tap/click on "Open snap" to view the DifRe image you just snapped. You can save or share the snapped DiRre image by pressing and holding on it (or by control or right clicking on it).