Could you get those videos on here? Maybe a screenshot of task manager, too.
I can't get any skipping from doing what you've said, even at higher resolutions. Both "desktop" and fullscreen work about the same for me (see
this picture), though it does spike a little more in fullscreen. In that picture, I was moving around the gmap on Unholy Nation for about 5-10 seconds each. Does it happen in smaller resolutions in fullscreen, like 640 x 480? Check task manager for any programs that are using your CPU up, and also try raising Graal's priority since you can't view task manager while in fullscreen (maybe you have a program that doesn't like Graal being in fullscreen).