Scorsese and Spielberg?
If this documentary is from 1971, those two weren't even famous yet. Why would they be interviewed for this documentary?
"We played with life and lost." - Jules et Jim, François Truffaut.
It was probably the new, restored and extended version, you watched.
From http://www.imdb.com/title/tt0066997/ :
"Runtime: 99 min / 110 min (restored longer 2006 version) / USA:110 min (2006 version)"
”Draco dormiens nunquam titillandus”