Background video doesn't start after page is loaded

Hi everyone! I wanted to use background video and everything works fine when I run the “Toggle Preview” button. However, the video does not start automatically when I switch to another page using the navigation bar. Additionally, the video does not automatically start when the page loads. This is driving me crazy. Please help!!! Please!!!

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

Hi Wojciech, welcome to the forum! Does this happen on a published version of your site as well, or just in the designer?