Primer

After watching Primer twice more with a new audience (once with director's commentary, which does contain some plot clues after all... even if Carruth deliberately avoids simply explaining everything), and reading the message boards (at one point printing out someone's multithreaded plot timeline) I have a pretty good idea of what the hell's going on, finally.

On my second viewing I picked up more individual details, but still lost my grip on the story at the same point as my first time through, I think: the scary scene of the boys concluding that the girl's dad has been using their equipment, and confronting him about it. From that point on, the characters suddenly seem to know a lot of things that the audience doesn't. But, all the information's there for one to piece together. (The trouble is that half the information is in earlier scenes, and you're not necessarily looking for it. The director's commentary points out a lot of these bits.)

The movie has an odd way of answering the causality/paradox problem, it turns out. I'm not sure I aesthetically approve of it, but the film uses it with careful internal consistency, and quite ingeniously. I think that it also explains the title of the movie. (The word itself doesn't appear anywhere in the film, as far as I can recall.)

On the other hand, I do like the idea of recursivitis as a physiologically manifesting illness. Kind of like the bends, for time travel.