1. Run Join (Merge, Combine) Multiple MP4 Files Into One Software.
2. Click the "Add MP4 File(s)" button to add files. Then an open file dialog will appear, hold CTRL or SHIFT key to select multiple files. To add all files in a folder, click "Add All MP4 Files in Folder" then select a folder.
3. To start joining the selected files/documents, click the "Start" button.