star trails video
What you're looking to do is a time lapse movie. You set the camera up with a timer and take a few hundred shots. I've done a couple but not the star trails as you've linked us to.
The free program I used to stitch the pictures together with is Windows Live Movie Maker. If you don't have it you can find it with a Google search. It's bundled with Windows Live Messenger and a few other programs. (I am of course assuming you're on a PC and not a Mac)
Just click the 'Add videos and photos' button under the 'Home' tab. Take note, have all your images labeled in sequential numbers.
Once your images are loaded, click into the 'Edit' tab. There you will find a duration setting. I usually use a duration of 0.06 for all the images.
Play around with some of the other settings and see what you like.
Once done, click the little file image to the left of the 'Home' tab, select 'Save Movie' and then choose the format you wish.
Try a few different things like a different duration or effects.
Here's one I did: http://youtu.be/PuvOjZzqhP4