How add a thumbnail to a video in github's README file and that shows the thumbnail on mobile

Question

I drag videos to the readme file and it's great because the user can play the video without leaving the repo's page. However on mobile it does not show a thumbnail of the video, see snapshot attached for this repo (safari ios 15.5 iphone 12). How can I add a thumbnail that shows when the repo is viewed on mobile and it does not take the user to another page when plays the video? Thanks