Webm video embed suddenly stops working

I’ve been playing around adding my own transparent video on this template (Webflow - Secret Project)

I’m hosting my webm video on AWS S3 and it all seems to work fine when I upload it into the custom code embed. However, each time after 5 or so minutes the video suddenly disappears… It’s very confusing! Am I doing something intrinsically wrong within my code / AWS settings?

Thanks in advance !

Here is my site Read-Only: Webflow - hen-ry