FSN must have some deal where they get to broadcast round 1. The last couple years they blacked the game out for me on NBCSN and so I had to watch the HS level broadcasting crew of FSN. If they didn't black out NBCSN, only about 1 in 10 people would watch FSN.
It's included in the NBC TV deal that local RSN's get to broadcast round 1 in their areas, with NBC having exclusive rights to everything from rounds 2 and on. Previously, local RSN's were able to broadcast rounds 1 and two.