Okay, so while this person does exploit glitches for their speedrun, that's not really what this one is about, but I think it's really cool and deserves to be shared anyway.
Over 1 year to create - this video combines 5162 attempts to speedrun Super Mario Bros. I recorded 193 hours of attempts (and practice) on an original 1985 Nintendo Entertainment System - then I wrote a custom computer program to process those videos and combine them via machine learning and conventional image processing techniques.
Watch it here:
And here's the "behind the scenes" on how the video was made:
And finally, the technology built for the above video was used and adapted and built upon to combine all 275 speedruns from speedrun.com/smb1 that got a time of less than 5:00 into a single video.