They work but inconsistency. At first I thought it had to do with whether or not MC was maximized on the screen because they began to work as soon as I restored down MC. But I couldn't get them to fail again when I maximized MC. There doesn't seem to be a consistently repeatable way to fix/break the key responses.
I did disable iTunes from using the keys by using the code in the OP's post. Before doing that iTunes would always launch whenever I hit one of the media keys.
open a terminal window and type the following commands:
to disable iTunes using the commands in dfortney's post:
> sudo chmod a-x /System/Library/CoreServices/rcd.app/Contents/MacOS/rcd
> killall -9 rcd
to re-enable:
> sudo chmod a+x /System/Library/CoreServices/rcd.app/Contents/MacOS/rcd
Peripherally related to this post, since my primary goal is to use the media keys via IR, I am going to try this USB/IR receiving device and see if I can consistently activate the keys (via software) using an IR remote.
https://flirc.zendesk.com/hc/en-us/articles/203689115-What-is-Flirc- It's right around $23 at Amazon. I realize it's not a viable solution for the problem with the physical keys. But maybe it can help point the devs in the right direction.