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 Pokemon one requires no almost advanced execution, other than turning off the console at a precise point to corrupt the save data you otherwise just need to follow a simple (though long) series of steps. The Mario one requires some pixel-perfect precision, and runners often used hacked ROMs that display coordinates in order to train. The Zelda one requires exact angles to be held on the analog stick, and I've heard of people creating guides out of cardboard and rubber bands in order to help them achieve the angles more reliably.
Sorry that I don't have any video links on hand, but you could almost certainly find examples of these in the GDQ archives.
EDIT: Found a good video for the SMW example, by SethBling, which actually goes a step further and manually reprograms SMW into Flappy Bird: https://www.youtube.com/watch?v=hB6eY73sLV0
EDIT 2: Here's an excellent explanation of the Zelda ACE: https://www.youtube.com/watch?v=wdRJWDKb5Bo