Keynote

Add live video in Keynote on Mac
You can add a live video from your Mac’s internal camera to a slide. You can also use an iPad, iPhone, or other external camera as a live video source. During a presentation, the live video plays only when the slide it’s on appears. You can turn the live video source on and off at any time.
Important: External cameras or devices must be connected to your Mac with a cable to record live video. During a multipresenter slideshow, only the cameras or devices connected to the host’s computer can be used as live video sources. To learn more about multipresenter slideshows, see Play a slideshow with multiple presenters.