I found a demo here, download it, burned it on a disc following the tutorial, then I realized it said "Mixed Media Disc". I went to my All Games Folder and didn't find it. I looked up a tutorial and it did the same thing but it had the old dashboard and it worked. Is this outdated and not working on the new dashboard?
Maybe show screenshots of the the files / folder you have on the DVD to see if we can spot if where went wrong. I presume you did unzip the demo first before burning it?