I've tried moving, but it didn't help. I didn't really expect it to, really, because the jpg that was created is named (1).jpg (after I downloaded the video again, cutetube created (2).jpg). In /.thumbnails, the jpg's names match the video file names, and since my video is not called (1), it doesn't look like it will work. In any case, the user shouldn't have to move jpg's manually, no?

The video does appear in the Archive and it plays, it's just that the thumbnail is incorrect (a picture of a film reel, which I guess is the generic thumbnail in cutetube).