you can do exactly what they do by injecting a save into the game.....it doesn't prove they have the game saving, only loading which is what anyone can do by injecting a save made on a gateway card or MT card into the rom
that video was only put out to mislead people into thinking pokemon is playable......i would hardly call loading the game and never being able to save playable though imo
the fact it pops up "the 3ds system has changed" pretty much suggests thats exactly what they did