Allen reading "Kral Majales" at City Lights Bookstore, San Francisco, probably early 1966. Neal Cassady sitting by his side. Jerry Aronson had compiled sections of this film for inclusion on his Life & Times of Allen Ginsberg documentary, unfortunately now out of circulation since it's distributor went belly up earlier this year.
2012 - The You Tube video referred to in this posting has been taken down. A brief excerpt from that with-Cassady-at-City Lights footage may be viewed (see "Interviews and Extras") here