Some of you may be able to browse to the play (51.2 seconds 2nd half) here: Virginia vs. North Carolina.

It's never explained, but I swear this is what happens. Virginia player has inside position and tries to grab the rebound, but is contacted from behind by a UNC player. Instead of calling a foul Pat Driscoll gives the ball OOB to Virginia. As he is about to inbound Roy Williams asks him to go to the monitor. Pat knows that the ball was probably off the Virginia player, so he goes to Jamie Luckie and Michael Roberts and talks to them. Luckie appears to be the crew chief and tells Roy they are not going to the monitor. Driscoll talks to Roy a bit more, but they return to their spots and Virginia keeps the ball. Very strange sequence.