Well, it wasn't my attention that kept me from watching "History Lessons" at its total length (I already got through much more static and difficult films), it was merely a mental barricade. Very often when I watch films like this one (often "essayistic" films of an explicit intellectual nature) I get totally disgusted by an aloof, bigheaded attitude which I think sometimes (in the worst cases) even has some kind of fascist character. The latter wasn't the case here but it really made me ill. I can't stand films which obviously try to avoid to cooperate with the viewer in any way or (worse) select their viewers by certain criterions- even if I'm still pleased with such a film personally (I still do like some of Godard's films...), I often can't get rid of the feeling that it's inhuman. Art should be humanistic, not cynical.
But I don't think of Jean-Marie Straub and Danièle Huillet as "evil" beings like Godard (the "Demon of Arthouse Cinema" he certainly is, imo) and looking forward to enter their work - I've read somewhere that "History Lessons" is one of their most challenging feature films, so it might has been not a good film to start.
Btw, when I posted this information, I thought of arsaib who understands French quite a bit (as far as I know). Also, A might be interested as he's such a big Fan of Straub / Huillet.