Demo (short for "demonstration") is a file containing a complete recording of a match, preserving the game engine's data: player positions, their aim, utility used, and round economy. Unlike a regular broadcast recording, a demo can be reviewed from any camera angle, paused at any point, and watched from the perspective of any player on the server — not just the one whose screen was shown to viewers.
Demos are the primary material for game analysis. Analysts and team captains watch them to understand how an opponent plays out rounds, which combinations they use on different maps, and where they typically throw utility at the start of a round. Based on this kind of breakdown, anti-strats are prepared — pre-planned counter-moves against a specific team. Without demos, this work turns into guesswork: it's practically impossible to spot patterns in an opponent's play relying only on memory or fragments of broadcasts.
Why players watch demos themselves
Besides analyzing opponents, demos are used to review one's own mistakes. A player can rewatch their own death from another perspective and notice what they missed in the moment: not hearing footsteps, reacting too late to a flashbang, standing in the wrong spot. Coaches review demos with the whole team, breaking the match down round by round and discussing decisions at every stage — from the start of the round to its conclusion.
In the situation involving the Brazilian team Legacy, who entered a tournament without a captain, the importance of demos becomes especially apparent. Reviewing the opponent's demos is usually a task handled specifically by the captain or a designated analyst. When there's no such person, the preparation work gets distributed among several players, and it becomes crucial that someone still takes on the systematic review of recordings, rather than relying on finding solutions as the match unfolds.
The word entered Russian-language esports slang directly from the English "demo" and is used across almost all disciplines — from shooters to strategy games — wherever the game engine allows saving and replaying complete match recordings.