GP was wrong about tapes, but plenty of these systems use hard drives already. They can use specialized drives that are cheap and have slow write speeds, because streaming video is a constant rate per second. They also don’t record unless there’s movement. The network is also a limiting factor.
I don’t think SSDs solve any problem, here.
We’ve already hit a perceived user experience limit. The perception of responsiveness in blind tests between SATA and NVMe SSDs isn’t always apparent–people sometimes say the SATA drive is faster–even though the speed difference on paper is substantial.
IMO, programmers haven’t exploited the possibilities of extremely fast mass storage yet. The orders of magnitude difference in speed isn’t fully realized. It’s not just faster, it’s faster in a way that requires new approaches. Unlike multicore CPUs over a decade ago, this change in thinking has gone relatively unnoticed by programmers.