How can I add a full page video background to my online store?

[TheLabeled]

Hey! I really want a full page video background for my shop, but haven't found the code for it or clear instructions on applying it. How can I make the entire website (or at least the home page) have a moving video background with products and other sections on top? Thank you in advance! Any help is appreciated. Here is an example of a site that has the type of background I want..

https://spidersinmycloset.com/