Hello,
The exec_pull and exec_push directives belong to the RTMP Nginx module:
https://github.com/arut/nginx-rtmp-module/wiki/Directives#exec_pull
The Nginx shipped with the kaltura-nginx package includes this module since the 12.4.0 release, which had Nginx version of 1.10.2-1.
If you are using an older version of the package then you will not have this module. What version do you have and what is the error you are getting?
As for your question:
Who would know if not me? I am the one doing it, after all:)
The full specs for all Kaltura CE are publicly available so you can see them here:
RPM spec file:
And specifically, this is the configure command:
deb rules: