I guess it all depends on how much $$$$ you want to spend...you could record your playing on Sonar or Cubase or something similar and then video yourself playing the tack...you can then sync the video to the music...If you're trying to record an acoustic then get a sure sm57 mic and it will sound wicked.

As for buying a camera with a mic good enough to get the guitar sounding good...to be honest I wouldn't know...and wouldn't even try it...as far as I know video recorders have mics about as good as a webcam...

If your serious then be prepared to spend some money and buy the right kit...!!!