Johnny's announcement refers to: firefox-45.2.0-1.el5.centos.src.rpm firefox-45.2.0-1.el6.centos.src.rpm firefox-45.2.0-1.el7.centos.src.rpm
The linked rhel webpage refers to: firefox-45.2.0-1.el5_11.src.rpm firefox-45.2.0-1.el6_8.src.rpm firefox-45.2.0-1.el7_2.src.rpm
These do not appear to be the same thing. Note the numbers just before the .src part of the filenames.