Determining aperture value used in a 5DII video
I'm not sure if this has been discussed before or not, but I think
you can determine what aperture was used in a 5DII video by checking
the exif data in the .thm file (which is a small jpg "thumbnail" that
is generated along with each video).
It doesn't display the shutter speed, but it does have a setting for
"Aperture Value" which seems to be correct.
I am extracting the exif data using a perl script called "exiftool"
directly from the .thm file from the command line.