Hi,
It is not a Kaltura issue, the libxvidcore4 package is taken from the ATrpms repo as is and is placed in the Kaltura repo to save end users from the need to add that repo. Regardless, different versions of RHEL/CentOS distros place ldconfig in different locations, which is rather stupid but nonetheless true. For instance, on RHEL/CentOS 6, it is under /sbin/ldconfig, whereas, on 7, which is what you have, it is placed under /usr/sbin/ldconfig, further more, it seems the change was made AFTER releasing the first glibc package for RHEL/CentOS 7, glibc is the package that provides the ldconfig util.
Anyhow, to make a long story short, I have now built my own version of this RPM and pushed it to the RHEL7 Kaltura repo. it will probably take a while to sync to all CDN edges but, rather than wait, you could do:
# rpm -Uhv http://installrepo.origin.kaltura.org/repo/releases/rhel7/RPMS/x86_64/libxvidcore4-1.3.2-16.x86_64.rpm
And the continue the installation as normal.
Let me know if you need any further help or run into issues,