Julia - the default frame rate for the VideoWriter object is 30 frames per second (see VideoWriter class for details).
I noticed that you put a one second pause in your for loop. If you want only one frame to appear per second, then you just need to set this rate in vidObj
vidObj = VideoWriter('pr_lgm_r1_ccsm4.avi');
vidObj.FrameRate = 1;
open(vidObj);
Try the above and see what happens!
