Looking for a good free recording program

Hi,
I've been wanting to make a tutorial for one of my CASUC reactors for a while now as someone asked for a video tutorial about it, but that project has been set back for a couple of days just for the simple lack of time as I've had quite a lot of reading to do. Now, when I finally have the time, I would like to know if you know any good, or even decent, free recording program that I could use to record an about 10-15 minute tutorial on minecraft?