You've probably corrupted your windows installation. Or at least the file sector fragment containing your video folder. The only way I ever get any corrupted thing fixed is to format the drive.

chkdsk isn't going to recover video, all it's going to do it literally grab every bit of data flagged as dirty and drop it in a folder as a recovered file... i can't remember the extension it will be, but it won't be avi, and it won't be readable as one. probably .raw or something.

if you wanted to recover that video, you actually destroyed it by running chkdsk. some other 3rd party recovery software could probably have grabbed all of that and put it back together (but not necessarily as one chunk). I've had that happen on an external before that I kept all of my divx/xvid movies on. Was a write caching that went bad and it killed the drive's TOC. I actually bought some software for like 25 bucks that recovered most of the movies. It probably got like 675 movies out of 700.