help!

I've finally had time to download the Post Mortem trailer and when it completed downloading and I tried to open it this message popped up :
The Compressed (zipped) Folder is invalid or corrupted.
Does anyone know what that means? Also, does anyone know where I could find a copy of the Dark Eye? I've been looking every where for one, but I read on Just Adventure that the company who created it, Interscope, no longer exists so it's very rare to find a copy, so obviously you can only buy used ones. It doesn't matter to me though, just as long as it's runable! Thanks alot!