Chrome and Firefox won’t load header video in Twenty Seventeen theme.

I’m making my first WP site starting with the Twenty Seventeen theme. I’d compressed an mp4 down for the Header Video and it was working great on Edge, but when I checked on Chrome and Firefox it wasn’t.

It just flashes my Header Image and sits on a dark grey background. I compressed my video all the way down to 1.9 MB thinking it was the size, but when I selected it from my Media Gallery I noticed little tiny text in the preview window (in the Header Media sidebar) saying “Error loading this resource”. Makes me think that it’s not the theme, but I dunno.

I only have the default plugins that came with the GoDaddy WP hosting and they’re all up to date. Any ideas?