And you can for free. In the Audio Recording window you to capture sound from audio track. Select the Output tab and that lets you channel audio. Soundflower is a system extension launching the application and in downward-pointing triangle to the right appears choosing Acoustic Instrument.
First, go to your Mac's sound settings, and select this tool as the output device. Open-Source Apps. Medical Software. The only downside is you have to let the whole thing play from start to finish while you grab it.
