If you do want to use your laptop then you need something called a "video capture card".
For a desktop PC this can go inside the case, but for a laptop you need an external one.
Here is a picture of an INTERNAL one (if you had a desktop PC)
http://www.maplin.co.uk/Module.aspx?ModuleNo=2 18064&&source=14&doy=search
Here is an EXTERNAL one
http://www.computervideo.net/dec04-1.html
Note that video takes up a LOT of hard disk space and it may be your laptop does not have a large enough hard disk.
It also needs a lot of computing power so your laptop may struggle unless it is a recent one.