Here's the clip (cropped):
JetBlue 20 is the culprut, but if you listen carefully, it's a confusing instruction.
JetBlue starts at ZA and cleared right C, 13L, D, right B to the ramp (WA). Jet Blue's callback is C, 13L, D. (If you look at the charts, that doesn't make sense)
ATC then gives him E B to the ramp to confuse things even more....piolt must have thought he was cleared into D, however, he was asked to hold at B @ D when Both JB20 and JB1061 didn't have a gate.
Piolt was in error to simply enter D....his inital entry was WA, and he was to hold short of D. I'm guessing JB1061 was still on Delta waiting for a gate.
JC