p.s. you will need the paid version AndroVid Pro, to work with longer video files.

I was just able to do this directly on my Android phone (S6 Edge) without having to use a PC to merge the mp4 files. The Android app is called AndroVid Pro. Use the MERGE function in the app to select both large GoPro video files on your phone and it will output to single, amalgamated MP4 file. Then...