That's neat. I wish they would just take the inputs from each player instead of a whole video stream. Kaillera did it fifteen years ago with emulation, it could be done and save some bandwidth
That's not technologically feasible without spinning up an entire virtual machine with clock-cycle specific control (i.e full CPU emulation) to run the game in. Kaillera could do it for emulators because the emulator itself could be controlled by Kaillera, i.e how many frames it runs and when, and any other operating environments such as system time controlling deterministic behaviours like random seed generation.
You can't do that directly with an independent program because that program itself has direct access to behaviours such as the system clock, and also indirect behaviours that are even more nuanced such as delta time framerate compensation for physics engines which introduces non-deterministic results. And that's with me trying to
simplify the problem, it's a very deep rabbit hole from here on.
