1) Go to scratch.mit.edu
2) Start a new project
3) Add the Video Sensing Extension to your project (button in lower left of Scratch interface)
At this point the Scratch website should ask for permission to use the camera and then the camera should switch on in the project background. This is what happens in Safari. But in Orion there is no permission popup, nor does the camera switch on if set to 'Allow' instead of 'Ask' in Website Settings.
Compatibility mode doesn't help.