Hi @lhjohn,
There are settings as part of Edwiser Homepage Builder that should help you replace it with your own animation.
Follow these steps,
Enable "Customise this Page" button on the Dashboard,
Go to "Site Home" page on your Moodle site,
When you are on the "SIte Home" page, click on the "Gear" icon which will be visible on the right bottom corner.
screenshot-remui.edwiser.org-2019.08.12-15_11_11.png
Out here you can add your won animation file under the first setting "Upload loader image for frontpage"
Once done save its settings and this should get the job done.