YouTube proved to be a great resource, since optical effects and expression by abstraction continue to be (are always) fascinating.
See especially Marcel Duchamp's famous and influential Anemic Cinema of 1926.
(Some of the comments left by viewers show much less responsiveness to this material today than when I was young—or John Cage)
This stuff (perhaps what Stalin's USSR objected most to) was both serious and fun, and by 'serious' is not meant any specific message (except in early post-Revolution Russia) beyond a cheekily anarchic stance and free association, at the same level as Duchamp's puns, such as the 'screen name' 'Rrose Sélavy (i.e., Eros, c'est la vie) and all those spiral texts: innocent youthful fun, surely. But the free association is indeed intentional. Richter, later, does not trust the viewer to make his own associations and so limits us by giving his own. The same is true of most of the dissertations written on Man Ray (in my opinion). And first hand diaries and letters make it plain that the students of the Bauhaus had a lot of fun. Depriving art of its play is depriving it of its soul.
Searching for these brings up also the YouTube postings for Leger's Ballet Méchanique and for the later plain OpArt that is part of the succession to Dada and Constructivism. Notice how much of the 1920s work is a mixture of traits from all the movements current in the wake of World War I. It is the enchanting effervescence of 1920s movements that made me admire Kentridge's work, too.