Tool-assisted speedruns. People use emulators and record inputs frame-by-frame, allowing nearly perfect performance and even reliable exploitation of game vulnerabilities. I remember one where the author exploited a bug in such a way that it completely reprogrammed the game:

http://tasvideos.org/5384S.html

Check it out, it's incredibly fun:

http://tasvideos.org/

There's an entire category for movies containing arbitrary code execution:

http://tasvideos.org/Movies-C3050Y.html