Why do I have .SEC files? (YI 4K Action Camera) .SEC files are much lower in bit-rate which allows you to quickly preview videos on the app. Related articles Why do I have .SEC files? (YI 4K+ Action Camera) What is a .thm file? What is the bitrate for each resolution? How much space does each minute of video take up accordingly? How do I download videos and photos from the app?(YI 4K Action Camera) Which FOV viewing angle mode can be available under each video resolution in the camera?