http://youtube.com/watch?v=h8mCwLx3N9Q
Here's THE Sega Megadrive add I remember from my childhood. According to the guy this was back in 1992, but noting that I was only 4 back then , it must've been around 1994-1995 (Or then I've seen in on a VHS)
The nintendo commercial I recall contains scenes of Mario in his raccoon form doing random stuff and a clip of Bart playing nintendo :/