Mac – “PROGRAMMING KEYS” Microsoft Ergonomic Keyboard 4000 / Mac Mini OS X 10.9.5

The function keys work because they are system-wide "media player control keys". Keystrokes always go to the system, which usually passes them exclusively to the active application, but some have special handling. There's a chance that you could reconfigure VLC so that the system-wide media key that means "rewind" does skip back instead. Check that out.

Otherwise you're going to need some kind of additional keyboard shortcut app like QuicKeys. (See also these suggestions). Don't give up yet! You almost certainly can cobble together a solution.

The reason for this is that Microsoft Keyboard Helper is somehow not being added to the Login Items by the keyboard's driver installer. However, the helper is contained inside the Microsoft Keyboard Preference Pane, so it is being run when you open it, and thus restores the full functionality of the keyboard.

The simple solution is this:

1. Open System Preferences;
2. Go to Users & Groups > {your user} > Login Items;
3. Click + icon under the Login Items list;
4. When Finder window opens, press ⇧ + ⌘ + G;
5. When a form appears, paste this into it: /Library/PreferencePanes/Microsoft Keyboard.prefPane/Contents/Resources/;
6. Select the file MicrosoftKeyboardHelper, and press Add;

That's it. The keyboard should now retain its function keys' functionality after the restart.