Models run weird

I added some models to my server, such as http://www.garrysmod.org/downloads/?a=view&id=17740 , and when a player picks that model, and others, they run really wierd; with there arms out and they dont move there legs. They just kind of “glide”. Is this a server side thing, or are the models just messed up?

EDIT: I do not know if this goes in server hosting or here. If it does go in server hosting, please dont ban me, but move it for me. Thanks in advance.