The download in %post approach is generally accepted as worse than adding some kind of script/software that the user can execute after installation: http://lists.opensuse.org/opensuse-packaging/2012-09/msg00248.html

Agreed, I will redo this using https://build.opensuse.org/package/show?package=autodownloader&project=home%3AMailaender%3Abranches%3Agames which has a GUI progress bar, a button for the user to start the process, Mirror support and MD5 checking.