You can add a video of yourself speaking in Google Slides now. Here’s how

In my opinion, the most helpful use case for this feature would be to share it with your colleagues so they can watch it asynchronously while still having the opportunity to watch you present. Luckily, you are able to do so with the “Rec” button, found in the top right corner of the toolbar. 

Once you click on it, you can click “record a new video,” which will bring you to a new page where you can click through your presentation, see yourself in the upper right-hand corner, and click Record to start. You can click through your slides, change your background, pause, and more. There is a 30-minute limit.