My schoolmates and I from Downtown Community School were there to see Captain Video do his stuff from 1949 to 1955. Dumont Studios was directly on the way home from school, and I stopped in every early evening to watch the live broadcasts.
I tell the whole story on this site in a webcam interview. This was one of the most important science fiction shows on tv for two reasons; it opened the way for Star Trek and many other shows, and it featured Galaxy Science Fiction Magazine writers such as Damon Knight, James Blish, Jack Vance, Sir Arthur C. Clarke, Isaac Asimov, Cyril M. Kornbluth, Milt Lesser, Walter M. Miller, Jr., Robert Sheckley, J. T. McIntosh and Evelyn E. Smith.