Not sure how original it is. I made this account just to ask this and probably get shot down. I've seen so many TAS's now though the most fun to watch IMO is still Super Mario 64. After I saw the TAS of Sonic 3 and Knuckles where Tails was controlled as well, I wondered if you could use TAS for all sorts of hilarious runs.
Prime example, MARIO PARTY! Where all 4 characters are used towards the prime objective of collecting as many stars as possible in the least amount of time to 100% the game. In my head, this sounds like a hilarious idea though I've had oddball ideas that only sounded good until I said it out loud. I have to wonder just how fast this would go. Obviously, you would use luck manipulation to get to the stars as quickly as possible. On a stage where there is a star space that jumps around, you could use all the characters to get them all faster then you would alone without risk of them getting stolen.
Not to mention, the minigames would be hilarious. You'd just let the one with the least coins win every time. Then again, you would probably choose the games yourself using luck manipulation and just cash in on the most profitable minigames over and over again and spending them on stars the next turn.
Just a stupid idea I had. I have to wonder why it hasn't been done before and thought I'd bring it to the forum =P