At MMA events, there is rarely anything to pay attention to besides the fight. It's not like an NBA game, where there are cheerleaders and mascot races and dance squads and staring at Derrick Rose's knee to will it towards healing. (Maybe that was just my last trip to an NBA game.) At fights, you watch fights, and maybe the big screen at bigger UFC or Bellator events.
The singularity of events means you really shouldn't miss a knockout. Even if you look down for a minute and miss the punch, you generally don't miss the fighter laying on the ground and medical staff tending to him. You don't miss it, unless you're this woman employed to be a ring card girl.