How can I make earphones with full inline controls work with VLC/Spotify?

I just wrote a simple Mac app to solve this problem. Give it a try.

(Tested on Mac OS X EI and Sierra. Not working for 10.12.4.)

It's an old question, but I've founded a partial solution to remove the automatic launch of iTunes: http://www.thebitguru.com/projects/iTunesPatch

More info and source code here: https://github.com/thebitguru/play-button-itunes-patch

It's better than nothing

There is a small app that remaps bluetooth headset controls to media keys (those on the keyboard). Fixes this bug on Yosemite with Spotify, VLC, Amazon Cloud Player.

https://github.com/jguice/mac-bt-headset-fix