"I don't think it's real, infact, I don't see how it could possibly be. Models are different, scale is wrong"
Thats precisely why it looks real.
Theres no way you could have actual mario galaxy on the DS.
But a a lower poly version is probably just vaguely possible.
DS only has 3000ish polygon limit, 6000 if you do two pass's a frame, but that restricts you in other ways.
As for texture filtering...yes, doing that on the ds in a practical game would be hard. (it would have such a insanely low frame rate).
However, with the compression, I dont think it has texture filtering in this video.
Its hard to tell, but if a fake is this realistic and with such effort, unticking a filtering option on max/maya/whatever isnt going to be much effort.