In this video I used the identical lens (24-105mm f/4L) on both the 5DMKII and 7D. Due to the 7D's cropped sensor I had to visually match up the focal length to match the 5D's setting of 50mm.
Unlike my previous two split-screen videos (piano & pool table), the two cameras here were NOT recording simultaneously. I captured video at all ISO's with the first camera, then switched and did the same test with the other. This was the only way to set it up using the same lens.
Every 5 seconds in this video the ISO will shift from 100, 200, 400, 640, 1000, 1600, 3200, 4000, 5000, 6400, 12800. The camera's were both set on Manual and after increasing the ISO I then adjusted the aperture to bring the exposure meter back to the middle. I kept the shutter speed at 1/60th since I was recording at 30fps. On the very last ISO setting (12,800) I had to bump the 5D's shutter speed up to 1/125th to get the exposure centered since I couldn't bring the aperture beyond f/22.
With regard to noise, they both seem to be equally matched until about ISO 4000, where it looks like the 5DMKII pulls further ahead as the ISO increases beyond that point.
Sharpness seems to go back and forth. At some ISO/Aperture settings the 5D looked sharper and at others the 7D looked sharper. I'm not sure why that is and might do another test sometime this week to see if I get similar results.