So by hard-coding, do you mean make it part of the JWPlayer declaration in the HTML so that people can see it when they inspect element?
From the article you listed above, you would need to change the
RTMPMediaProvider.as file and enter your shared secret in this file. Your shared secret should
not be part of the JWPlayer HTML declaration. You would then need to compile your customized player using Flex SDK/Builder according to JWPlayer's build instructions.