Okay, I feel so stupid about this, but I just downloaded DeskScapes and then spent a whole morning trying to determine why my Dream wallpapers weren't moving on my desktop. (This included looking into codecs and other techie things that I really don't understand.)

Then I realized something: I was running DesktopX! Surely it doesn't support animated wallpaper. Yep, I exited out of DesktopX and my wallpaper was immediately animated.

I hope I'm not the only one silly enough not to think about this. I just wanted to put it out there in case anyone else ever had the same issue.