ok, stupid noob question alert!

I went through the fire ring tut. and while my system can render the whole thing in no time, I cannot seam to get it to render into a AVI file! when I went into the render options I selected the AVI option, but after running batch render, no file! I even searched my entire hard drive to make sure I did not send it to some strange directory but it just plain did not create... what the heck am I doing wrong?