1. Go to Settings
2. Click Advanced in the left sidebar, and click Privacy & security.
3. Under Privacy and security, click Site settings.
4. Click on Camera, Microphone and Pop-ups and Redirects to allow site to ask to use camera and microphone and send pop-ups and redirects.
You can also set which camera you wish Opera to use by default if you have more than one connected to your computer. Use the dropdown menu to set your camera preference.
Set the permissions as shown below.