It's actually pretty simple to join two video files in Audio Trim Split Merge Edit. You have to first install and load the software, then use the available buttons to add the necessary videos in the main interface. Once they're added, the videos will appear as thumbnails on the left side of the app. Select the videos that you want to merge, then tick the Merge option on the bottom of the same column. Choose the output folder and start the operation. At the end, you will have one single file merged from two videos.