In the case of Spotify (%APPDATA%\Spotify\spotify.exe --> converted to hex & written after "hex(2):" to be able to write a default REG_EXPAND_SZ or Expandable String Value using System Variables) and the Media (♫) button (which by default call the *.cda or AudioCD associated app) just save the following code in a *.reg file and execute it.
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD] "BaseClass"="Drive" "FriendlyTypeName"="@shell32.dll,-10144" @="CD Audio Track" "EditFlags"=hex:02,00,10,00 ".cda"="CD Audio Track" [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell] @="play" [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell\open] @="&Open" [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell\open\command] @=hex(2):43,00,3a,00,5c,00,55,00,73,00,65,00,72,00,73,00,5c,00,64,00,61,00,6e,\ 00,69,00,65,00,6c,00,2e,00,64,00,65,00,6c,00,67,00,61,00,64,00,6f,00,5c,00,\ 41,00,70,00,70,00,44,00,61,00,74,00,61,00,5c,00,52,00,6f,00,61,00,6d,00,69,\ 00,6e,00,67,00,5c,00,53,00,70,00,6f,00,74,00,69,00,66,00,79,00,5c,00,73,00,\ 70,00,6f,00,74,00,69,00,66,00,79,00,2e,00,65,00,78,00,65,00,00,00 "command"=hex(7):46,00,6e,00,34,00,70,00,61,00,31,00,5a,00,63,00,65,00,38,00,\ 6c,00,51,00,21,00,52,00,56,00,6f,00,60,00,39,00,4b,00,2b,00,63,00,64,00,61,\ 00,3e,00,5d,00,34,00,73,00,6d,00,52,00,48,00,78,00,2b,00,7e,00,3d,00,46,00,\ 5f,00,77,00,2d,00,52,00,27,00,4d,00,2b,00,3f,00,6c,00,20,00,22,00,25,00,31,\ 00,22,00,00,00,00,00 [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell\play] @="&Play" "MUIVerb"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,\ 6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,\ 00,75,00,6e,00,72,00,65,00,67,00,6d,00,70,00,32,00,2e,00,65,00,78,00,65,00,\ 2c,00,2d,00,39,00,39,00,39,00,31,00,00,00 [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell\play\command] @=hex(2):43,00,3a,00,5c,00,55,00,73,00,65,00,72,00,73,00,5c,00,64,00,61,00,6e,\ 00,69,00,65,00,6c,00,2e,00,64,00,65,00,6c,00,67,00,61,00,64,00,6f,00,5c,00,\ 41,00,70,00,70,00,44,00,61,00,74,00,61,00,5c,00,52,00,6f,00,61,00,6d,00,69,\ 00,6e,00,67,00,5c,00,53,00,70,00,6f,00,74,00,69,00,66,00,79,00,5c,00,73,00,\ 70,00,6f,00,74,00,69,00,66,00,79,00,2e,00,65,00,78,00,65,00,00,00 Note 1: if you need to write a different Expandable String Value (because you want to launch a different app) you can follow these examples.
reg.exe add HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell\play\command /ve /t REG_EXPAND_SZ /d "%APPDATA%\Spotify\spotify.exe" reg.exe add HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AudioCD\shell\open\command /ve /t REG_EXPAND_SZ /d "%APPDATA%\Spotify\spotify.exe" Note 2: if you need to know what your key is doing I recommend you to analyze the whole process with Process Monitor.