What can I do to stop the Play / Pause button from opening iTunes?

a better temporary fix is to start quicktime and just have it running(not playing a movie) in the background. It uses less ram/cpu than iTunes.

"The real solution: Open Terminal, paste in the following line, and hit enter. You're done. To undo, change unload to load in the same line.

launchctl unload -w /System/Library/LaunchAgents/com.apple.rcd.plist"

"Renaming iTunes only works until OS X finds it again. I deleted it from Applications and a couple of minutes later it was found on my backup disk and the problem returned. Deleted it from there to, no more problems. Don't forget to emty the Trash, or it will probably be found there...

So, deleting all copies works fine for me. My music is flac so I have no use for it anyway."

"I have a 'workaround':

Quit iTunes
Locate iTunes.app in Finder (In Finder: Menu › Go › Applications...)
Ctrl-click on the iTunes.app-file and select 'Compress ""iTunes.app""' (for backup)
Ctrl-click on the iTunes.app-file and select 'Show Package Contents'
Locate the file 'Info.plist' inside the folder 'Contents'
Ctrl-click 'Info-plist' and select 'Open with..' and select 'TextEdit' (or your favourite text-editor. Not Word tho.)
Near the bottom of the file locate the following segment:

<key>CFBundleIdentifier</key>
<string>com.apple.iTunes</string>
Change the last 's' in the word 'iTunes' to 'z', like so:

<key>CFBundleIdentifier</key>
<string>com.apple.iTunez</string>
Save the file
IMPORTANT: Drag the file 'iTunes.app' out of the Applications-folder and on to the Desktop
Drag the file 'iTunes.app' back into the Applications folder
(You should probably disable the iTunesHelper. This can be done by going to System Preferences › Accounts › (Your account) › Login Items and remove the 'iTunesHelper'.)
Log out and log in

I hope this works. It works for me!"

"For Snow leopard users:
Ok i didnt find an answer for this problem, but i tried to work my way around(for people who wants to watch videos on VLC and pause it with the apple remote/keyboard and itunes keep opening)
option 1:
open itunes and let it run but click on itunes store and hide itunes or minimize it. continue with watching videos on VLC and music won't play.

option 2:
Use Front Row to watch all your videos. To do so install PERIAN for quicktime(which allows you to play all formats in quicktime) and put all your movies in your ""movies"" folder. Enjoy watching movies through front row.

option 3:(this one worked partially. )
Rename itunes in applications folder to ""itunes_off"". In order to do this you might need to make your user privileges to"" read and write"". right click on itunes and click on ""get info"" then go in privileges and click on little lock icon, enter your password and then change your user setting to ""read and write"". After this rename itunes to something else. But this solution didnt work correctly for me. it stopped opening itunes for a while but when i restarted my mac it started opening it again.
Try if this works for anybody.
And keep me posted."