This video is about spindle hard drives. With one having SSD as well for the OS and spindle for storage in one unit.
I knew there were a bunch of HDs out there. But I wasn't much to look into what and why. Though now it make sense. There are HDs for an everyday computer. One for a speedy computer. One for network attached system, where files are being accessed constantly. Then there are ones that are being written to constantly, just like a 24/7 DVR for video surveillance.
So are you using the right drive for that NAS, or video surveillance you just installed?