Hey there. Sorry for the extremely late reply. It's rare when I get comments here so I don't always check the notifications for it. I am the same person who posted the Sonic Adventure AutoDemo. I found it on a Japanese site that was selling it off. It looked very unusual so I bought it. Not realizing what it really was until I ran it on a Dreamcast. It was then dumped using a Dreamcast and some dumping tools for the Dreamcast. Many thanks to everyone who put so much effort into researching it.
You're very welcome. Glad to be of help :3