Let me clarify my earlier comments.
There are many problems with his technique and (ahem) interpretation, even if we only define interpretation to mean the basic principles of music, foremost of which is maintaining a steady tempo. Mario tunes are not representative of the greatest art in the world, obviously, but even the simplest of pieces are based on basic musical principles.
None of these problems bother me, really. This is fun music and was played for fun, etc. I was smiling as I watched it, partly because it reminded me of the good times I had as a kid playing this game. This guy is not selling himself as the greatest musician on the planet; not every pianist has to have an international career as their goal. He is simply having fun. I have nothing against him, and I applaud him for his accomplishments.
But, I am a teacher as well as a pianist. Since most people on this forum are asking questions and searching for answers related to technique and musicality, and since most of these questions pertain to the very basics of pianism, it is important that the budding pianists out there are able to identify what is good and what is bad about whatever they are listening to or viewing. I am simply cautioning those who are struggling with certain aspects of technique or musicality to avoid using the Mario guy as their example or guide. When pianists view that video and then proclaim that it represents great playing, I feel a sense of duty to warn them that they should look elsewhere for examples of correct playing. Let's keep our standards high.
Robert Henry