Cleveland unexpectedly forced Dallas to overtime, and after an incomplete pass to Miles Austin with 8:35 left to go in the extra period Cleveland called timeout—presumably to force a replay from the booth. Cleveland thought the play was a catch, fumble and Browns recovery. Almost immediately, CBS went to commercial and when Gumbel and Dierdorf returned, we heard Ed Hochuli explain that the previous play was not a reviewable play, that a timeout to Cleveland was charged and "...and the ruling on the field stands—although as I said it's not a reviewable play, I didn't review it."
As Football Zebras puts it, "[b]ecause the call on the field was a play-killing call, replay cannot overturn that call and add a subsequent action." In other words, since the replay could not reverse the call on the field to make it a completed pass and also then add a fumble recovery by the Browns, the play was not-reviewable.
After the ruling was made, Dierdorf mentions that Hochuli went to the replay hood saying the play was under review, so presumably the booth buzzed down to Hochuli. Maybe Ed set the booth straight and informed the officials this was not reviewable. Or maybe Hochuli and the booth merely discussed that the play was not reviewable—it's unclear. What is clear is Hochuli's amusement over the suspension of disbelief required for the whole thing.