On Wednesday Ivo Blom will talk about the Filmliga's séance practices (at the VU). There is no required preparatory reading, but a relevant text is Tom Gunning, "Ontmoetingen in verduisterde ruimten. De alternatieve programmering van de Nederlandsche Filmliga," in: Céline Linssen, Hans Schoots, Tom Gunning, Het gaat om de film! Een nieuwe geschiedenis van de Nederlandsche Fimliga, 1927-1933 (Amsterdam: Bas Lubberhuizen, 1999), pp. 217-263. A highly bizarre interview with co-authors Linssen and Schoots, who seem to confuse the project of a critical historical reexamination with some kind of juvenile debunking exercise, is here.
A good general introduction is still provided by Jan Heijs' inleiding to SUN's 1982 reprint of the Filmliga magazine, which is here.