create quick audio screenshots from whatever your mac is playing
^⌘Space starts/stops recording
NB: this is still alpha software—it's guaranteed to be unstable.
run the installer.
open Audio Midi Setup, right-click on WavTap, select "use this device for sound output"
open WavTap, click on its icon in the menu bar, make sure "Built-in Output" is checked
make uninstall removes everything