I saw a Video Wallpaper on a few of Althemy's websites... How do you guys do that?

I think it's just copy/paste the YT link in the background box. Right?

I think it is that simple

I was scrolling on forum and see this. How havent I had a clue
So anybody can do this ? only on sites?

Video background can be implemented only through your site (created on Althemy) yes.

Its default feature accessible over style switcher (panel) on your Home page.
Feel free to create site and try this interesting option.

disclaimer: Currently we provide connectivity with YouTube links.

What interest me is: Is there any chance of posting gif or a timelapse as a video background?

To be honest with you Catwhisperer, no chance at the moment.
It is on development agenda yet all major platforms that are using that are differently customized than us.
We still need to polish few things before we approve usage of those containers that can be troublesome for system...

Bottom line .gif or any qt7 related material (such as hyperlapse etc.) will be supported in single update.

We'll keep you informed

I have question about this: Is a video background slowing down opening of a website?

Not at all Scarlett
We had an opposite idea. To offer the best possible experience by letting people link existing video storage and channels to their sites.
Altogether it will not overload the your Althemy site, thus offering smoothest playback experience.

Thanks for asking such constructive questions