- Find the mp4 file you want to include in your slide in your Google Drive.
- Take a screenshot (Click on it in your drive to bring up a preview window and then Shift-Command-4) of the video to serve as a hyperlink placeholder to your mp4 file.
- Go back to Google Slides, and find the slide you want to add the video link to.
- Insert the screenshot you just took.
- Downsize the screenshot as you see fit for your slide.
- Select the screenshot and insert the hyperlink.
- You can do this with CTRL + K (on a PC) or Command + K (on a Mac).
- Paste the shareable link of the mp4 file in Google Drive.
- Click Apply once you’ve pasted your link.
- Now, your image is hyperlinked to take the user to the video located in Drive.
Here's the video that explains it.