You can speed things up a bit by playing back with the -timedemo rather than -playdemo command. Depending on how fast your machine is, this will result in a speed up of between 2 and 3 times normal speed. By hitting the '-' and '+' keys, you can change the screen size to speed things up even more. On my P166 the smallest screen size is about 6 times normal speed, this basically gives you a fast-forward button. The disadvantage of -timedemo is that the playback is always faster than normal, and you can't go into map mode.
Use a pause button! I just learned this recently, maybe everyone knows about it. Play back from a Windows 95 full screen DOS window. If you hit the "windows" key in the middle of your recording, it will take you back to W95 AND playback will be halted until you go back to the DOS window.