This guy, aqwawaf, made an assisted speed run of four different Mario games running at the same time. Then, he posted the video on Youtube. This video uses four NES emulators all hooked up to a single controller input. The only way to get something like this accomplished is using emulators and save states to tweak Mario's every twitch. This is what's known as a tool-assisted speed run. It's technically possible for a human being to actually perform these movements, but the timing would have to be so perfected that it's virtually impossible. Luckily (?) we can manipulate emulators into doing all sorts of strange stuff these days. If you don't know your Mario games, he's running through two copies of Super Mario Bro's on the right hand side. The left hand side has Mario 3 and Mario 2 stacked top and bottom.