ProPresenter 7 on Mac may ask you to grant permission to access the Camera and Microphone when attempting to use a Video Input for the first time. In order for this process to work properly, you need to turn the Audience and Stage outputs off.
Not all video inputs require permissions. If you are using Blackmagic Decklink or UltraStudio devices, you may not be prompted to grant permission. However, if you add a USB capture device or use the Facetime HD camera, you should get these prompts the first time.
If you attempt to activate a Video Input and still have an external screen activated in ProPresenter, the security prompts will look like this. If you see these, verify that Audience and Stage both have red dots next to them above the Preview. If Audience is green, press Command-1 to turn it off. If Stage is green, press Command-2. Once you have granted permission, you can re-enable your outputs.
These are the wrong alerts.
The two security prompts that you want to see look like the next two images. Click OK on each prompt to grant the correct permissions.
These are the correct alerts.
You can verify that ProPresenter has the correct permissions by opening System Preferences, clicking on Security & Privacy, and checking the Camera and Microphone lists. Click on each in the left column to see what apps you have granted permission to.
If you ever have issues with cameras or need to revoke permissions for some reason, you can do this by opening Terminal and entering each of the following commands followed by enter. These remove ProPresenter's permissions from Camera and Microphone.
tccutil reset Camera com.renewedvision.ProPresenter
tccutil reset Microphone com.renewedvision.ProPresenter