Question:
backgrounds and videos are not auto playing.
Product:
[Which editor or feature is your question most relevant to? e.g. Wix Editor, Wix Studio Editor, Editor X.]
What are you trying to achieve:
I want them to autoplay
What have you already tried:
[Share resources, forum topics, articles, or tutorials you’ve already used to try and answer your question.]
Additional information:
They auto played before but not now. they are set up autoplay and also loop. When I click the preview tab they autoplay but when published they dont. I have looked a the site on a few different browsers and the same issue. The videos are small in size only maybe 20mb. You have to click on them each time to play.
i have similar issue… but no one helping out 
Came across this discussion while helping some others out 
This may be a browser limitation, as it’s generally considered bad user experience to have videos auto play on a site. Browsers will sometimes restrict this behaviour, and can also be impacted by a users own device settings (e.g. power saving mode).
Why is it considered bade UX?
It’s to prevent situations of catching a site visitor off guard - for example in a public space, like a train or bus, where they inadvertently have their audio enabled, and a video starts playing. It causes situations of fluster where that person was unaware the video would start playing.
That said, the setting will work, but depends on various factors.
There are many prominent sites that auotplay silent videos, such as ILM.com. I bought a Wix subscription based on the Wix preview of my site showing it could autoplay my landing page video. But then it’s disabled when you publish the site. It wasted a lot of my time developing a site with a fake functionality that gets yanked away at the last minute. The Wix autoplay option is a lie and should be removed.