index.html

<style type="text/css">
   .video-wrapper {
       display: none;
   }

   @media (-webkit-min-device-pixel-ratio: 0) and (min-device-width:1024px) {
       .video-wrapper {
           display: block!important;
       }
       .video-fallback {
           display: none!important;
       }
   }

   @supports (-webkit-overflow-scrolling:touch) and (color:#ffffffff) {
       div[class^=video-wrapper] {
           display: block!important;
       }
       div[class^=video-fallback] {
           display: none!important;
       }
   }

   #MessageViewBody .video-wrapper {
       display: block!important;
   }

   #MessageViewBody .video-fallback {
       display: none!important;
   }
</style>