Wll, actually, Main and Elm have no corner in common- they are parallel, one block apart.
The cam is actually "...the ONLY LIVE view available in the world from the Sniper's Perch. EarthCam's live webcam gives you an exclusive view from the sixth floor window of the former Texas School Book Depository in Dallas, Texas. "
It is at the corner of Elm and Houston, "caddy-corner" from the Dallas County Records Building.
...three miles from BRONS, clear for the ILS one five approach...