You should read the manual first:
http://www.soldat.pl/manual/manual-en.html#KOMENDY
quote:Commands from a parameter:
These are parameters that can be used when running Soldat.exe:
(...)
- Soldat.exe -demo name (freecam speed notexts extract)
(runs the game and plays the demo specified by name. Optional paramaters are:
freecam (0/1) - the user can freely change the camera (default 0)
speed (0-...%)- how quick the playback will be specified in percents (default 100%)
notexts (0/1) - no texts, menus or cursor will be displayed during playback (default 0)
extract (0/1) - extracts the demo to BMP files (default 0). Later they can be used to make an AVI file in a program like "Bmp2Avi".
The sound can be extracted with a program like "Total Recorder". Please note that this can take time and is not recommended on slower systems. For better results specify lower speed (like 50%).
example:
Soldat.exe -demo demo12
Soldat.exe -demo demo19 1 200 1 0
)
or search the forums when the manual doesn't help you:
http://soldatforum.dnagames.net/search.asp
Demo help...
Demos
How do I play soldat demos (was: HELP!!)
Demo Recording
the easiest way to play a demo is to use a tool called "DDplayer". You can find it here: http://archive.forums.soldat.pl/topic.php?topic_id=10725 it's easy to use and you have all the available options for playing demos.
or you could just open Soldat, go to the "Join tab" menu, enter the demo name (without the .SDM ending) into the IP field and enter Port: 0
now click "Join game"