Newer FFmpeg prohibits 4096x4096 MPEG-2, presumably because it violates
the standard.
http://git.videolan.org/gitweb.cgi/ffmpeg.git/?p=ffmpeg.git;a=commit;h=7fb87bc5f24b1be13269109506c05e4c54695b5e
(cherry picked from commit 424a7b0ab0)
Conflicts:
modules/highgui/test/test_ffmpeg.cpp