I was amazed at how simple it was, as many things seem once you know how it's done I've got a pad on my laptop, but when I saw this I wanted a bigger one. I haven't built one yet, but I might go shopping for a webcam. They're about US$40 on ebay, The biggest touchpad I could find was the standard.(I didn't look very hard) There a are open source or windows programs which can be used as trackers.

Below is the url of the open source program (the free one) that is mentioned in the clip. There are instructions on how to install the open source program, it isn't an exe file, but the instructions for windows, linux, and mac are at the touchlib site, and seem fairly straightforward
http://nuigroup.com/touchlib/