Before starting the installation of FFMPEG kindly check whether the following has been installed
1. ruby-1.8.7.p72-5.3
2. ruby-devel-1.8.7.p72-5.3
3. autoconf-2.63-1.97

To verify try the below link
# rpm -qa |grep ruby
# rpm -qa |grep autoconf

If not available install it through "yast" (Media required) or download the rpm packages from Software.openSUSE.org

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SanS