When I launch Parallels Desktop, Facetime Camera on my Mac doesn't work anymore, I have to restart the Mac to get it back to life.
This is a widespread issue on macOS Sierra and Parallels Desktop 12 for MacBook Pro 10,1 laptops caused by Sierra camera conflict, currently it's being investigated and worked on.
As a temporary workaround, please follow the instructions to fix the issue:
Make sure you have macOS Sierra installed on MacBook Pro 10,1.
To find out click on Apple logo > About This Mac > System Report > Hardware > Model Identifier.
Download the following file archive: Fix.
Locate replug_facetime.zip archive in your Downloads folder and unzip it.
Open Terminal.app (Mac menu bar > Go > Utilities).
Start Parallels Desktop then launch a virtual machine and wait until Windows is fully loaded.
Execute the command below in Terminal:
System will ask to enter your Mac password, please do so (note: the password will not be seen due to security restrictions), then hit Enter.
NOTE: By running this fix you are resetting the Facetime camera. You should apply this fix each time you want to use the Facetime camera along with Parallels Desktop.