At the 2013 Gamescom in Germany, Stabyourself.net recorded 974 people playing their custom Super Mario Bros. time trail level. After collecting all 974 playthroughs, they merged them into a single chaotic video that evokes nostalgia as all 974 players simultaneously run, jump, and try to survive in a race to the finish line.
There was a 3 second penalty for dying which explains all the frozen Marios. Also note that enemies and objects may not appear synced to the players – that is due to the way Mari0 (and the original SMB) works. Best time (blue Mario): 41.32 seconds
video and image via Stabyourself.net