Thanks for your input. I ended up using a video because I did not want the transparent PNG to look like a mask, and having a layer scaling over a background video would be noticeable. My work around was to find the appropriate width for the video file itself. You can see the updated version (links below).
The website is basically done but I do have an idea to implement an interaction on one of the pages, which I am not really sure how to set up. Maybe you can help. 
Question is here: Help With Scroll Interactions - Section Scrolling Over Section
Here is my site Read-Only: https://preview.webflow.com/preview/the-marsupials?preview=99fa04172f119fa742908e315e6114ff
Here is my site Published: http://the-marsupials.webflow.io/