Comment by michaelt
A 4k 30fps video sensor capturing 8 bits per pixel (bayer pattern) image, is capturing 2 gigabits per second. That same 4k 30fps video on Youtube will be 20 megabits per second or less.
Luckily, it turns out relatively few people need to record random noise, so when we lower the data rate by 99% we get away with it.
1. I believe in modern cameras it’s 10+ bits per pixel, undebayered, but willing to be corrected. Raw-capable cameras capture 12+ bits of usable range. Data rates far exceed 5 gigabit per second.
2. Your second paragraph is a misunderstanding. Unless you really screw up shooting settings, it is not random noise but pretty usefully scene data available for mapping to narrow display space in whatever way you see fit.