The media does loads properly in Chrome, the Anki editor and when reviewing. But the localize media addon hangs with “Unexpected response code: 400” on invoking.
I believe the problem is that Anki is seeing a & and converting it to &, which is what you’d normally see in a query string. But that site is strange and seems to expect an &. I’m fear changing the existing behaviour would break other use cases, so you’ll need to make the necessary modifications on a local copy of the add-on - reimplementing _retrieveURL() from Anki and stopping it from calling unquote().