to ask them for support. I haven't seen anyone here offer support for sites that are buggy. That is, you always get sent to them to ask them to fix their app.

Why only this site? I'm sure if I google "How to download Vimeo videos?" that there are other solutions. Try other solutions as there ways.

Finally you mention "format." VLC Player plays your link for download just fine. VLC Player can also transcode the format if required.