While I do think Nintendo do have the right to do this. I wouldn't say that the situation is the same as uploading music and movies. With music and movies if you upload them you aren't doing anything yourself you are just copy pasting. While in games you are playing the game, you are manipulating the characters. It's more comparable to remixing a song in my opinion.
Many we'll agree to that, but this is how we think. The business world doesn't work like that.