That's absolutely insane. Manipulating the state of the game world so that its data maps to instructions to complete the game, and then glitching in a way that executes it. The only thing I'm not clear on: even knowing exactly what you're doing... how likely is it that you could pull this off in real-time? Did the player have to do this 10 times? 100? 1,000?
I don't know about the run shown in the OP, but there are a fair number of memory-manipulation/ACE speedruns that are feasible in RTA ("real-time attack", a.k.a. something a human could pull off, as distinct from TAS). Off the top of my head I can think of such routes for Pokemon Red/Blue, Ocarina of Time, and Super Mario World. To answer your question of "how likely is one to pull this off" for those three, the Poke…
Mega Man 1 has an ACE category as well which is really interesting. I think Nudua explained it somewhere. (On my phone, but a quick googling should help you.)