[Problem]: When I wanted to install any repo using yum command, I was getting error because of which nothing was getting installed properly through Yum command and I was using centos 6.4.

I was getting below errors.
[Error]:

 [Solution]: After long long struggle with various provided solutions at Google search, finally it started working. It appears that it has installed RPM Fusion repositories for Fedora, rather than for Enterprise Linux. These would not be compatible with your CentOS system, so it would cause this error.
Here are few working steps which would solve the above said error.

yum  repolist enabled

will show you the below image (Make sure you have the permission to use yum else do su – or sudo –I before using yum command) :

[root@AlienCoders ~]# rpm -e rpmfusion-free-release rpmfusion-nonfree-release
warning: /etc/yum.repos.d/rpmfusion-free.repo saved as /etc/yum.repos.d/rpmfusion-free.repo.rpmsave
warning: /etc/yum.repos.d/rpmfusion-free-updates.repo saved as /etc/yum.repos.d/rpmfusion-free-updates.repo.rpmsave  

Either use above given link or use below command to install correct rpmfusion package.

su -c 'yum localinstall --nogpgcheck \
http://download1.rpmfusion.org/free/el/updates/6/i386/rpmfusion-free-release-6-1.noarch.rpm \
<a href="http://download1.rpmfusion.org/nonfree/el/updates/6/i386/rpmfusion-nonfree-release-6-1.noarch.rpm">http://download1.rpmfusion.org/nonfree/el/updates/6/i386/rpmfusion-nonfree-release-6-1.noarch.rpm</a>'

[root@AlienCoders ~]# yum repolist enabled

You can see at the above image that rpmfusion* is showing RPM Fusion for EL 6. Now, try to install anything through yum command, it would work fine.
Hope this would solve other users problems too.