Why is Gif/Video loaded by browser although set to invisible on mobile

Hi, I have Gif/Video Hero section for my site. You can check it here: https://doodance.com/
But it is only showing on Desktop & tablet. To reduce load time on mobile, I set the Hero Video Section to

  • Display settings: None AND
  • Visibility settings: Desktop & Tablet only

Here the Share Link to my site: https://preview.webflow.com/preview/doodance-relaunch-2018?preview=d73d1fe873d0f4fe637188f488bae9bf

But when I checked Load Times with the Chrome Developer Tools for mobile, I notice that the Gif/Video is still loaded on mobile.

How can I prevent that from happening? The Gif should NOT be loaded on mobile.

Thank you all in advance for your help!