I figured I'd make a tutorial on extracting the audio when dealing with multiple tracks. Especially helpful when you want to edit your mic/system sound in post!
First thing needed is to download DXTory. Yes, I know. I'm advertising another recording program; but trust me, Action! is much more efficient and has features that DXTory lacks! Find the download through Google. The trial version will work just fine!
Once the program is installed, find the video file with the multiple audio streams.
*Note: This will only work with AVI recordings.
Right-click the video file to reveal the context menu item called "Extract Audio Stream". Let it process, and when it is done, you'll have the WAV files. Each WAV holds an audio stream. In this case, we have two. One for the system audio, and the other for the microphone stream.
Finally, you're ready to import the WAV files and the AVI file. Here you can edit the streams' volume levels, which is helpful if you can't hear yourself over other audio sources.