Is this CentOS 7 or 6?
You have to install EPEL from a separate Repository.
Script Save As -> simplescreenrecorder.sh
using nano or vi command
To Run in your Present working Directory type
This will execute your Script / GitHub Is good as well to save scripts.
Or USB Key in a jewelry box in a safe.
Present Working Directory
Always verify the link to download use lynx
yum -y install lynx
yum -y install epel-release-7-10.noarch.rpm
rpm -Uvh epel-release-7-10.noarch.rpm
Not always verify
Or try from source using the source file .tarball
make, make install, ./configure
Try the Readme Docs from the main site
Oh by the looks of it is not in that repo its in ATRPM.REPO