I've been watching Summer Games Done Quick all week, and although there have been a whole lot of great moments -- Zelda: Oracle of Seasons was awesome! -- my favourite runs so far are the Mega Mans.
Between the crazy strategies and the tight little tricks that help these guys shave a few seconds off their final times, all of these speedruns are super-fun to watch. And each of these folks knows every second of the games, which is incredible to witness.
Above: Mega Man 3, by Checkers. Below: Mega Man (Adefgames), Mega Man 5 (Darkman78) and a Mega Man 6 race between Go1den and Darkterrex. Videos via GDQArchive.