Yep, it gets confusing when you are using, say 12/14/16-bit RAW or TIFF and 24-bit jpegs, but the Jpeg has the smallest gamut.
The real issue is the video formats, most cameras can do much more bit depth (my mono astro cam is 12 bit) for greater dynamic range.
I suspect the GoPro gets greater bit depth images and plays with the data to maximise the dynamic range over 8 bits for jpeg and mpeg as many cameras and phones (with HDR type processing do real time processing is ridiculously capable these days).
For planetary images I generally use 8 bit video (as it speed up capture, ideally going for high two or even three figure frame rates), as we stack multiple frames, and a couple of thousand is equivalent to 19-bit depth...