The IndyStar has a feature today showing stills of the play from the angle it sounds like Red Zone may have had. The live feed and all the feeds I saw from the press box side were inconclusive to me that Chapman tripped the runner. From angle in these stills though it does appear the contact was made.
Anatomy of a Play: Blown call costs the Colts in Cincy
Triplett never said the replays didn't show this part of the play. He just said he didn't look at it. We don't know what he did or didn't see.