To some people, just the idea of poutine—a gloopy mixture of French fries, cheese curd and gravy invented in winter-addled Quebec—is surreal enough. And then there are the ads: But what does it mean?

We often forget that many cutting-edge modern artists found funding and support by making ads. The work of New Zealand avant-garde filmmaker Len Lye is a case in point. His films, like “Rainbow Dance” ...