You might be thinking of "A Disney Halloween", a 90-minute special that combined clips from "Disney's Halloween Treat" (narrated by a pumpkin) and clips from "Disney's Greatest Villains" (narrated by Conried's Magic Mirror). Both feature the same "Disney's Halloween Treat" theme song. Both are pretty terrific. I also like Disney's "DTV's Monster Hits" - a bunch of Disney-themed music videos set to pop music. My kids love them.

As far as I know, none of them are available through commercial means. You might check the bittorrent community for those titles.