Videos are uploaded from a stored folder on your computer. Video must be MP4 files and must be less than 15MB. Additionally, the ideal size is 468px wide 350px tall or larger at a ratio of 4:3.
Click the "Media" message part, and then "Video". Click the video box to take you to your Drive, choose your video and open. Wait for the video to upload and finish - a still of your video should now show in the box.
You can also link to a video using a button. Simply add a button to a text box, eg "Watch video 📽️", then open the button settings by clicking the cog.
Once your button settings are open, choose "Open URL" and then input the URL of your video:
Save the message settings and then the message. The video will launch in-app (on mobile) or a different tab (on desktop).