So I just upgraded from Snow Leopard to Mavericks. I used to be able to trim videos in QT (not the QT 7 in Utilities) and save them. But now when I try to do it, it gives me the message, "The operation could not be completed" Can someone please help? However, when I try to trim a MP4 file, it saves. I'm so frustrated. Is there any way to downgrade to the QT that was default with Snow Leopard?