• HDV native source clip captured in FCP 5 (seagull standing on wall in front of water).
• Exported from Quicktime Pro to AIC using 1080i preset.
• AIC layered on top of HDV using 'difference' transfer mode in FCP.
• Exported via quicktime conversion to uncompressed
• levels changed in AE with black input = 0 and white input = 5 to make differences visible
• Scaled to 50% and compressed with h.264 @ 7Mbit/second.

Original difference clip appears pure black - differences are only visible to the naked eye due to extreme stretching via levels.

Note half second rhythmic flashing - this is presumably from the I frames which seem to have approximately 40% of the pixels exhibiting no change at all.