I delete the .THM and .LRV files along with the MISC folder but what are they actually good for? THM is for thumbnails on the LCD so that is clear, and the rest?
LRV is a Low Resolution Video on the GoPro. You can use it on your not-too-powerful computer, edit, and then for the final render use the original, high resolution video. You can view it by renaming to .mp4
In an effort to make this question more about photography…
Protip: Change the extension of the GoPro
.THM files to
.jpg you'll have viewable JPG image files.
It's for the GoPro apps (iOS and Android devices). The apps will not work without these files because the apps use them to show you the live feed without major lag.