I tried ripping one episode of friends onto my hard drive on a new folder in the Mac HD. The file location is "/Movies/Movie.mp4" with "Movies" as the new folder name. I can watch the episode fine. (except the first one i ripped, missing the first part before the opening credits) But when i close Mac HD folder, and reopen it to watch it, it says the file isn't a movie file. What should i do?