Mario Twins follows in the tradition of
All Your Base Are Belong to us and
Something Awful in using the otherwise
benign Shockwave Flash technology for
evil, instead of
good.
Basically, it starts out as a typical conversation between two guys with outrageous Arab accents. After the intial revelation that one of them had just purchased a "new SuperNES system" (actually, it's an NES system, but hey, who's counting?). It then degrades into a debate about why, exactly, Mario and Luigi "look the same". Finally, it coalesces into the animation and beatbox-acapella rendition of the background music from level 1-1 and 1-2 of Super Mario Brothers for the NES.
There was another version of the movie, which had an additional "water" scene from the middle of the game, and the final confrontation with Browser. It also inexplicably featured throwing human excrements at a cat (and a toilet). After that, our intrepid Arab protagonists discover that the princess is in another house go away!!! This frustrates them so much that they decide to turn off Mario Twins and play a different game.
There is actually a website for this abomination: http://niftyhacks.zophar.net/mariotwins.htm. Make sure you're not trying to drink any sort of liquid as I was when you first view the movie, as you'll probably be liable to spit it out all over your monitor as you burst out laughing.