In the Quake series, Demos are "movies" of gameplay recorded by a person. Demos only record what happens in the game, thus making making file sizes relatively small.
In some cases, movies are recorded into .avi files for anyone to view.
These Demos load up with the game. Unlike a Single Player demo, these showcase some of the levels that can be found in the game. While a Single Player demo strives to complete the level, the Pre-Loaded Demos only show off a small portion of the level.
Single Player demos focus on quickly beating the game. Most of them have some sort of challenge added to it as to make things more interesting (such as only using the Axe).
Multiplayer demos are "frag demos"; they focus on clan and tournament matches. Most MP demos are not recorded as video files, thus they must be played from the Quake executable file.
- http://www.challenge-tv.com/ - The main archive of MP demos.