Is there a way to make it so the site header doesn't cover part of the background video?

Has anyone found a way to stop the site header from covering up part of a first section background video?

You can, but you'll need Custom code to accomplish it...

Managed it and thought I'd share my solution for anyone else dealing with this. 

I did a blank image section, set the row count to one, both gaps to zero, the height to one, deleted the default image, and set the background to the same color as my header background.

Then I identified the section id and inserted this bit of code on page's advanced settings:

<style>
[data-section-id="your section id number"]>.content-wrapper {
  height: 0 !important;
  padding: 0 !important;
}  
</style>