Occasionally on a Mac, the built-in camera does not turn on or is not recognized by the Chrome or Firefox browser.
Use these steps as a helpful work around solution to this issue:
1. Quit your Chrome or Firefox browser entirely (cmd+Q).
2. Open your Facetime app and leave it open.
3. Open the Chrome or Firefox browser.
4. Start your Session by either clicking the link in your email of copying/pasting the link into your desired browser.
5. You can now close the Facetime app if you want to.