Great question! The following article outlines how to record video with the FaceTime HD Camera in iMovie (2013):
Record live video directly into iMovie
1. Do one of the following:
- To record using the built-in camera: Click the Import button in the toolbar.
- To record using an external iSight camera: Connect the iSight camera to your computer with a FireWire cable, and click the Import button in the toolbar.
2. In the Cameras section of the Import window sidebar, select the camera you want to import from.
A live video image from the camera appears in the Import window.
3. Do one of the following:
- To choose an existing event to contain the video: Choose the event from the “Import to” pop-up menu at the top of the Import window.
- To create a new event to contain the video: Choose New Event from the “Import to” pop-up menu, type a name for the new event, and press Return.
Thanks for the follow up and additional information. The following resource may help to troubleshoot this issue further:
If the steps outlined in the above article do not resolve your issue, you may find more information by using another one of Apple's support resources - https://getsupport.apple.com