To people talking about how long it takes to recover the video, windows prefaces deleted files with a non-display character, depending on the formatting the string which represents such a character may or may not mark a deleted file, and simply removing it could cause damage, so what they do is run through the drive at a machine code level, index all said characters automatically (about 6.5 hours per 100 gigs) and then examine the code by hand, if it's determined by a forensics technician to be a file header they determine the sectors the file occupies, and then they attempt to recover it. Most machines have hundreds of thousands of deleted files, it can take weeks, maybe even months to properly analyze a hard drive. If you want more info try reddit's netsec, hacker, or computer forensics boards. There are multiple approaches to it, but blindly undeleting can have disastrous effects, you could have a missing bite of information (often from corruption), that causes a reading frame shift, so what looks like the character could actually be a completely different character.
Long time lurker, almost never poster here.