Replying to No Sound!

So, I've got a movie I really want to watch. I couldn't find it at any rental places, and I couldn't find it in any stores. I don't have a shipping address so my last resort was to download it.

Well, I got a nice high quality version of this 70s film, but when I open in (Quicktime with Flip4Mac, I'm on MacOSX) I get a message saying I need to download new codecs, so I checked and there aren't really any codecs that apply to what the problem could be. Like, I get video, but no sound at all. I had this happen before and I ended up just deleting the file, but I don't want to just delete this one.

I tried running it through DivX player and it wouldn't even open it, so I don't know what to try next, any suggestions?