[geeks] DTS or AC3 test video?

[Atomist]

Geoffrey S. Mendelson wrote:

>Hi, I'm trying to set up a surround sound system and need something to
>test it. I am looking for something I can download and burn to a DVD or
>CD (I want audio, don't need video). 
>
>The short demo at the begining of a THX movie is sort of what I want,
>but I would like something longer. 
>  
>
http://www.digital-digest.com/dvd/downloads/trailers.php

Google search for AC3 test files revealed that.