YAY I CAPTURED FANTASY SEAL -FADER-.
Btw ... VirtualDub can dub music ? 
Not really, but there's a way to add..."background music" to your video.
I'll use
one of my videos as an example. What I did:
-Record video with MUSIC TURNED OFF. Only sound effects.
-Open your recorded video with Virtual Dub
-File->Save as WAV. This saves the audio for the video (that is, the sound effects) as a .WAV file on your computer.
-Open Audacity. Open the song you want for your BGM and the audio from the video in the same Audacity window. File->Export as .WAV. This will save both the video audio and your BGM in the same .WAV file.
-Go back to VirtualDub. Audio->Audio from other file. Select the .WAV you made in Audacity and you should have both your sound effects and dubbed-over music.