How do I embed a youtube video in Keynote 6.6.

Hi JJJOakley,

Welcome to the Apple Community where some of us do our best to help each other :)

Apple have a Keynote User Guide online ... may guide you to add video to a slide, or to replace a media-holder.

https://support.apple.com/en-au/guide/keynote/tan63d61519a/mac

Hope this helps you achieve what you want to do :)

• With the YouTube video playing in Safari, right click on the video and select Copy Video URL
• In Keynote, go to the the Insert menu and select Web Video, in the text box that appears, right click the text box and select Paste, then click the blue insert button.