Hello. I have an experience with ActionScript 3.0 and with the video editing programming. I can create for you an AIR application that will do exactly what you need. I have several completed projects similar to yours (time trimming, converting, cropping, rotating, combining e.t). I will create friendly user interface and all you will need to do, it's choose folder with videos (or drag and drop needed files to the list) and set the trimming settings. In order to do this I will use the ffmpeg library. Thanks, Volodymyr.