The 728×90 banner ad unit is an IAB standard ad unit also known as is known as a Leaderboard Banner, Super Banner or just a Leaderboard. The leaderboard size 728 pixels wide by 90 pixels tall. A 728×90 ad is usually placed at the top of a page, so as to be seen by the user immediately when the page loads.
Expands down: 728x250 (Optional). Audio must be user-initiated. Default state is muted.
Regarding Nickelodeon and MTV, it only applies to the KCAs and MIAW microsites.