How do I play soldat demos? is there some sort of player? I have RKKLu but that isn't very good also I would like to know if there is some way of making them .avi's?

Welcome to Soldat Forums! If you want to watch a demo then start soldat. In the IP adress field u write the demo name. In port u wrtite 0 then click join game and u will be watching the demo hopefuly.
Beside use search and use ur soldat manual. And you should post this in Help Section.

use a program called fraps to record your demos into .avi's, and then you acn go and make movies and things.. there is actual demo players around, just use the search!

Here you go.
Use F8 to record\stop demos.
Diamond Demo Player 1.1 By Pr0ger :|