I too am having this problem… I saved some files to the root of the Public/Shared Videos directory. When I went to move them I was given the same error. I don’t see how to turn off Twony so I removed the Shared Videos directory from its grasp. Still no luck.
I ended up FTP-ing into the box using WINSCP using my admin credentials and one by one I was able to delete the files at the root of the Shared Videos folder. It seems that anything in a sub-folder I can delete.
