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.
|Ruby Red Dress by cjf2|
from High key portrait with RED
|Follow me home by eaa|
from Shades of Blue in Nature