Someone posted another video in another thread of the same play:
http://www.middletownjournal.com/sports/mplayer/m/73866
In this one you can see the official making the call -- and , as I suspected, he is trail.
When you see him enter the frame of the video, he is about a foot away from the halfcourt line. Pretty far away to make a good call on this play imo.
But, at least he sold the hell out of it!