I imagine you have got this covered as you have done this previously so many times but might be useful for people searching through these forums in the future. On occasion (usually when batch exporting direct from FCP and forgetting to check the right preferences when naming exported files) new files can be exported without their file extensions in their name. FIne for anyone looking at them on a Mac but will result in a call from a producer at some point soon after saying “there something wrong with all the files. The client can’t open any of them”. Problem solved by getting client to type .mov at the end of every name and blaming the world of PC’s but still a school boy error.