Why do that when you can chmod properly? Also, Unix-based systems use '/' not '\'. Also, if Apple didn't change too much, shortway to do it is just to use ~/ to represent home directory.
Edit:
Let me explain. The way you described the problem screams "permission error". I've tried giving read/write priveleges to my Urban Terror folder, but it won't work right. That's why, we should move it to a folder with correct permissions (and it's honestly EASIER to reinstall, which I'll do XD). However, *drumroll* unix base systems have permissions that actually seem to work right. Rather than moving files, it's way easier to just deal with the problem at hand: permission error.
There are two different problems described in this thread. Since I'm pretty sure i've seen powermad upload demos before I am assuming his issue is #2 below (not permission based) and I answered it accordingly. If his are not showing up anywhere then it could be permissions. Your problem could be either since you never mentioned if the files were being saved in the appdata directory (but I'd bet permissions if you are on win vista or 7 and running the normal build from urbanterror.info since the default homepath is correct in that build for windows)
1) Demos, Screenshots, Configs don't save at all:
This is a permission error commonly found in Windows Vista or Windows 7. Permissions are generally not an issue for Windows XP (since program files is not protected) or Linux/Mac since it's not "installed" but rather unzipped by the user creating the directory with the correct user permissions (hence the different "install" packages) Also when I had to do this it was just a matter or drag and drop to fix the permissions on Win7 but if reinstalling is easier then at least backup your config if you can
2) Demos are being saved to a different directory path:
This is
not a permissions error, its an "error" in the default homepath directory for the Urban Terror client. The client saves demos, screens etc in it's homepath, and if that's not set to your Urban Terror directory it will not save there. In Windows it can be set on execution the way I described and can be done similarly in linux. I would assume it's also possible on a mac but don't know the exact steps.