For this example, it shows a tooltip that is being hovered, but note that you can do this for ANY tooltip whether it's triggered from a hover or displays right away.
Here's how you do it.
1. First things first. Add your media asset (in this case we're adding a video)
2. Next, drag the tooltip inside the tooltip, and update Autoplay to ON, Controls to OFF, and Mute to ON --> These are the recommended settings, but they can of course be used however you prefer!
3. Last, add the video (or image / gif) to the tooltip group*!
*Not sure what the name of the tool is that you want to add the media? This article on Tool Naming should help!