Gif as a Wallpaper?

Yes, and you don't need another app. Go Apple icon > System Preferences > Desktop and Screen Saver and see if the gif is available in the folders presented on the left. If not, click the + in the lower left and add the folder that contains your gif(s).

So, i tried this but it said that it couldn't run it because it was unsupported

I'm afraid OS X does not provide for animated wallpaper. There are some apps that claim to do this such as DeskFun and BioniX. But I haven't tried them and don't know if they cause system issues. If you try one, let us know what you think of it.

deskfun works perfectly you can even make the gif transparent so you can see the old desktop under it!