Apologies - I got my figures wrong. It's about 60 GB per second at 6 million fps, 8 bit pixels, 50x50.

Actually, it's one two-billionth of a second. But in any case, still a huge amount of storage needed.

Frames per second is different than shutter speed. The camera takes images at a very high shutter speed. That doesn't mean each second has 60,000,000 frames - it just means that every frame depicts a slice of time which is 1/600,000,000 seconds small.