They are used to set correct stats at the beginning of each demo.
Before someone starts recording the next level in a constructed multi level run (such as any QdQ run), he execs the config file, so that he, for example, has the rocket launcher, some rockets, some armor and some specific health at the start of the level, as would be expected if the entire run had been recorded in one continuous take.
Generating config files is easy with demtool. [tt]demtool -i level1.dem level2.cfg[/tt]
Using the config file isn't complicated either. In quake, just type [tt]exec level2.cfg[/tt] at the console. Then when you start a new level, the stats will be set. Of course, this requires that you use the QdQstats progs.
Great! Why didn't I ask this question before. I always used to put all those settings by hand each time I started to record demos on new map. I'm working on my private qdqlite project, but it is slow crap