Unlike a lot of commercials on this list, this one doesn't have any particular significance (except that it reminds us of how much we all wanted to win a Nintendo 64 back in the day). It's just an extremely well made short cartoon that pretty accurately depicts how it felt to play Mario Kart, even though Mario isn't swearing as much as I usually am.
One of the biggest games of all time had an appropriately intense trailer. After watching this, I felt a powerful urge to run to Funcoland for some Funky Kong. However, I remembered that Funcoland is closed, so I opted to instead throw my hat on the ground and stomp on it.
Though the console wars of the 2000's have certainly been considered to be intense by some, they are a mere scuffle compared to the full-blown console wars of the early 90's, pitting 16-bit brother against 16-bit brother. There were so many good ads that one could make a whole separate list of "The Best 16-bit Attack Ads That Make You Say 'Oh No They Nintendidn't'" However, for the best example of complete ad bluster, look no further; the term "blast processing" means about as much as "triple hops brewed."
Sega fans waited so long for a real follow up to the Genesis that when it actually happened in 1999, it was a pretty big deal. Fortunately the "It's Thinking" ad campaign followed suit, making Dreamcast seem like a huge party in your bedroom that all of your favorite Sega characters were invited to. Nowadays the only place you can get that is, unfortunately, DeviantArt.
This commercial belongs on the list just for being incredibly humorous and memorable. But it deserves to be number one because it was America's introduction to the idea of Nintendo characters beating the crap out of each other, a simple, lucrative idea that became one of our nation's most time-honored traditions.