Lol, I have two 5Ds and two 7Ds...
But I realise I gave you a bum steer as I should have written TV mode to maintain to shutter speed with Exposure compensation. AV mode maintains aperture. I always use manual mode for video but often use AV mode for stills. The exposure compensation is dialled into the camera on the main command dial - you can see how much on the meter - it's all very simple.
Liam Hall
Director/DoP/Editor
http://www.liamhall.net