I would like to start simple recordings. I have a high definition video camera, and an acoustic guitar with an L.R. Baggs M1 Active pickup. I can plug it into my mac for garage band, and it sounds really good.

Now I was wondering, how do I go about taking a video with the camera of me playing, while using that same audio from plugging in the guitar to the computer.. so it is in sync..

clap your hands before playing your actual part, put the two in an editing program like Windows movie maker or whatever you have, edit out the clap but use it to sinc the two parts...

save the file as a mpeg or something...
I'd recommend playing an open note (close to the camera) but with the same procedure. The only thing that'll pick up your clap will be the camera itself, which is already synced.