well, i was just thinkin it would be helpful ... i mean, not all demos run for the full 20 mins of gameplay. some demos are just short clips, and others might be of matches that are won in under 20 minutes. it would be helpful to me, because i often sit down and start going through all of the auto-recorded demos that pile up in my demos folder - watching some of each one to tell what is going on, and if it's one i should delete or not.
instead of scanning the whole demo to determine the length, what about this: make it so that when a demo starts recording, an internal timer (which counts in seconds, maybe) is also started. then when the demo is stopped, that timer is also stopped, and its value is somehow included in the .dm2 file. would that be possible?
then upon playback, it would just start a visible clock at the value in the file and start counting down.