I often want to pause my iTunes music when watching a video in Safari. Currently on some sites (but not all) the Pause button starts controlling the video in Safari in stead of iTunes.
How to permanently link the buttons to iTunes?
BeardedSpice, solved this for me. It was intended to allow the media keys to control services in Chrome, but it also can lock the media keys to iTunes.
The touch bar is context sensitive and changes depending on which app is running. The touch bar will control the foreground application or the one that is currently active active. If you are watching a video on Safari the toucher will control Safari, to get it to control iTunes you will need to make iTunes the active application.