I've been using Lightroom video editing features for a while. Suddenly I was unable to play my video files in library module (no video was displayed when selected, play button was grayed out). Every once in a while "There was an error working with the video" was displayed. I am not able to export video as well. I've seen this sort of problem being brought up in Lightroom 5 can no longer preview or playback videos I had in my library but I couldn't find a solution to this problem.