Example of a 4-split screen can be seen in Singing Dog 2. It is basically 4 clips playing at the same time (see picture on the left). Other variations of a split screen, for example a 3-split screen are more difficult to do and will be discussed in other tutorials.
This tutorial is written for Adobe Premiere Pro 2.0 users. If anyone knows how to make this in any other programs or any other way, please contact me and I will add your tutorial/comment or a link to it.