I used Mobirise builder for my site. Then I published my project to the local folder on my PC and added Envanto theme. After that, I can stop background video. Did anyone have such a problem? Thanks for a response.
Contact with your item author hope they will help you out from your issue.
You are pretty lucky that this is the only issue you have combing proper HTML with page builder sites.
Unfortunately (it doesn’t sound like a particularly hard issue to fix), the author will not be able to help with 3rd party code so you may need to enlist freelance help from somewhere like www.studio.envato.com