When ND arranged to play 5 games a year vs ACC teams, ND was allowed to keep the NBC contract by the ACC, even though the ACC has their own network.
ND keeps all bowl money they earn for a bowl if they are selected on merit. Play off, NY6, etc. they had a huge windfall when they went to the BCS title game a few years ago.
They can also jump over an ACC team to play in one of the bowls that the ACC has agreements with. In that case, they split the revenue with the ACC.