Another thought, I bet a system like this would be really easy to upgrade to a curved track. This would be good for macro shots so you don't lose focus on your subject at the ends of the track.
I would be interested to see what kind of tripod head they used and how they attached it. That's really the one thing missing from this video. Can anyone share some other tutorials on properly mounting a tripod head to a slider like this? I just got a 65mm ball head and don't want to break it just yet.
Also, I am sure that the price is higher than it should be because of the skateboard wheels and bearings. As a skater, I have extras lying around my house, so it should be way cheaper for me. Wheels and bearings can cost around $40 at the cheapest.