You can't edit your files with Samsung Master 1.1 because the video formats supported by the application are WMV, AVI, MOV and ASF. In this case, there are two solutions for your problem. You can either convert the MP4 videos to a supported format, or you can use another video editor. In order to convert the files, I suggest you use VSeven MP4 Converter. It is free of charge and once you launch it, you need to press the Add button, select the MP4 file, choose an Output Folder and an output format, and press OK. If you prefer the second solution, you can try any program from the Software Informer database.