There are 2 interesting examples here of video from the Nikon 300s and Canon 7D specifically under artificial lighting conditions at night and the wave type issues that appear on the Nikon but not on the Canon 7D. You can see this near the end when the person is filming a shop with the Nikon 300s and moving down towards the pavement and back up. You see the wave effect for a few seconds before the camera seems to adjust and the video comes back to normal.
It seems the Canon 7D may have one up on the Nikon here! The below example from the Canon 7D is just amazing !
Think this just convinced me to save up for the Canon 7D for Christmas! Note that the rig used for the 7D is very impressive but cannot be considered a reason for the difference in quality of the video if you were wondering… He has added a lens hood / matte box, viewfinder and microphone and uses tripods, other stabalizer gear and last but not least this was shot at 1600 to 6400 ISO!