First, there is a lot of choppiness (short pauses) in the video delivery in HD mode. This is not what I'm talkiing about.
The frames in many of the shots, especially the long-focal-length shots, that look like inaccurate frame registration in old films. The frames jump around, up and down, side to side. The ballistics of the movement are unlike any i've seen in hand-help film or video, and must be the result of the IS system in the lens.
My conclusion, the IS system built into the lens is entirely inadequate for hand-held video shooting. The system is made to stabalize a short-duration movement, not movement in a long sequence, and sort of 'resets' itself when jostled giving the appearance of sudden frame shifts.
Some have made the argument here that the 24-105L IS lens in the kit is chosen over the 24-70L because the IS makes for better video shooting. I think this video demonstrates the IS motion artifacts are as distracting as the motion they are attempting to dampen out.
I'd like to see Canon address this in a firmware update that overrides the default behavior and changes the IS ballistics to work better for long sequences of video. It might not be possible. Corrections over a long time require a (relatively) large amount of IS correction movement, and the lenses simply might not have enough movement to work with (hence the frequent 'resets').
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Bruce Wilson, not a pro
http://science.uvsc.edu/wilson