NFL's stupid TV rule?

this is so stupid...im watching the Dolphins-Chiefs game...one minute left...chiefs down by a touchdown...and Greg Gumbel's sttupid voice comes over and ssays "by NFL rule, we have to pull you away from that game, but we'll keep you up to date"...WHY?!? what is so important to the NFL about not letting us see the last minute of the game? and why does greg gumbel get to see it?