It's difficult enough to hear/feel the sound even if you use the best of mics when recording, if you're lucky you may get a clue though. With that said, I think I also said that the mics in camcorders should be avoided. Or, try to use both, the camcorder mic for speech and the "real" only for the music.
What's also important, in the end, is how the video is rendered and presented. Most vidoes are compressed to the max (depends on how you set it up) - to get the file size down - and of course this also leads to poor audio quality. IMO the absolute minimum quality for MP3 audio or similar should be 128kbps, but preferable 192kbps (or more). I guess how good you ever will get the result in your computer, or on tape, this quality will be destroyed in the same second you decide to upload the finished work to Youtube or similar. So this case is not easy to solve
I hope you got some help of what's said above, and hopefully it wasn't totally out of the blue.
Good luck, Donner, you're doing a lot of good work!