Dolby occasionally posts "Unfold" and "Silence" trailers on their official Vimeo channel in high-bitrate ProRes. Search for "Dolby Atmos Unfold Vimeo Download." You can use a Vimeo downloader to save the MP4 (though again, it will be lossy).
The "story" of the disc is often told through its iconic trailers: Dolby Atmos Demo Disc Download