/record - starts recording a demo
/demo "demoname.dm_69" - plays a demo you have recorded
And /stoprecord stops recording demo.
/timescale (value) can be used to speed up or slow down the demo.
Demos are not videos, to record a video you should use some external app, tho /video and /stopvideo can be used while playing a demo (in game = lag), this would create a huge video file same resolution as the game, so you should set smaller res first if you use it.
