Background video does not show in mobile

I used a background video for my site and added a poster video for mobile devices as suggested here: https://extendthemes.com/knowledge-base/mesmerize-theme/knowledgebase/video-background-type-on-mobile-devices/

The video does not show in mobile, even though I do know that it is possible!

Quite tired of browsing forums: who can help?

The page I need help with: [log in to see the link]