Fedora only includes free gpl-compatible software. To use none-free software and drivers (Nvidia) you have to use at least the rpmFusion-Repository:
su -c yum localinstall --nogpgcheck http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-18.noarch.rpm http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-18.noarch.rpm
yum install kmod-nvidia xorg-x11-drv-nvidia
yum install vdpauinfo libva-vdpau-driver libva-utils