Undeleting a 5DIII movie file?
There's a free app that runs in the terminal in OSX that recovered some data for me. I think it's called TestDisk. Not sure if it will work for you, but I think it recovered some movie files for me. Not 100% sure since I was mostly trying to recover jpgs.
|National Gallery of Art by Kukla|
from Your City - Black and White (in colour!)
|Hummingbird and Bee by dibilio57|
from My Best Photo of the Week
|The Snowy Egret by Lee8282|
from Color - Monochrome
|Skate Boarder dpr-0927 by vbuhay|
from Skateboarding Cover shot