Ebert responds! http://blogs.suntimes.com/ebert/2010/01/a_riddle_wrapped_in_a_mystery.html
I think he's wrong though... i'm with bugaboo's suggestion that Haneke is the culprit, and the camera is hidden behind the fourth wall...
On I Am Dumb And Need Someone To Explain 'Cache' and Roger Ebert Please
Ebert responds!
http://blogs.suntimes.com/ebert/2010/01/a_riddle_wrapped_in_a_mystery.html
I think he's wrong though... i'm with bugaboo's suggestion that Haneke is the culprit, and the camera is hidden behind the fourth wall...