This free video merger can help you merge and concatenate your video files, it can join and combine multiple video files into one file. The tool supports various video clips, such as MP4, AVI, M4V, MKV, MOV, WMV and more. These files will be connected one by one in the order you entered. The generated video will have the same width and height as the first video file, and the other video files will be automatically resized to fit it. You need to select at least two files, the third and fourth files are optional. The tool will try to maintain the video quality and audio quality so that it can be as good as the source video files. In addition, if you need merge more than four video files, you should select the first four video files and create the first output file, then use this output file as the first file and attach the remaining video files, if you have many video files, you need repeat this process. The output format is MP4 video.