How much evidence has to be there to overturn an American football play?

Question

I was just recently (5 minutes ago) watching an American football game. It was a quite important 4th down play to win the game, and the play was challenged. The cameras had absolutely ZERO view of the ball; however, the ruling on the field was a catch. So, with NO view of the ball whatsoever, the referee's call overturned the ruling on the field. Wouldn't this just be 'The ruling on the field stands'? Can the referee who called the completion come back and say it wasn't a catch and he called it wrong on the field?

Basically, what goes into calling a play back from a challenge/official review besides what the cameras see?

Answer 1

The replay official is supposed to let the ruling on the field stand unless there is "indisputable video evidence" that the wrong call was made.

From the NCAA Football 2013 and 2014 Rules and Interpretations, Rule 12 (Instant Replay), Section 1, Article 2 (Philosophy):

The instant replay process operates under the fundamental assumption that the ruling on the field is correct. The replay official may reverse a ruling if and only if the video evidence convinces him beyond all doubt that the ruling was incorrect. Without such indisputable video evidence, the replay official must allow the ruling to stand.

Section 7, Article 1 (Criterion for Reversal):

To reverse an on-field ruling, the replay official must be convinced beyond all doubt by indisputable video evidence through one or more video replays provided to the monitor.

The NFL has similar language. From the Official Playing Rules of the NFL 2012, Rule 15, Section 9 (Instant Replay):

A decision will be reversed only when the Referee has indisputable visual evidence available to him that warrants the change.