He’s using the parallel port to capture data and feed it to the display software of your choice. The method depends on a custom kernel which alters the way the parallel port works.

Parallels Workstation is a new piece of beta software that allows the use of any version of Windows (3.1, 3.11, 95, 98, Me, 2000, NT, XP, 2003), any Linux distribution, FreeBSD, Solaris, OS/2 ...