Helping the jury find its place on the tape machine

In U.S. v. Pratt, the Fourth Circuit in an opinion by Judge Niemeyer concluded among other things that there was no error in allowing technicians to go into the jury room and cue up a part of the evidence on tape, that the jury could not find themselves. Judge Motz dissented on this point, explaining that the government must affirmatively prove that there was no harm in what was done.