The talk introduced and discussed a 35mm screening of the film and the event was part of the 2013 Greater St. Louis Humanities Festival.
You can read two of Jonathan Rosenbaum's essays on the film here and here. After that do yourself a favor and pick up a copy of his BFI Film Classics volume on "Greed".
The Turner Classic Movies version of the film is available on iTunes. I find Apple's inflexible DRM policy intolerable so instead you can opt to have Amazon notify you via email when the DVD version is released.