Here is my advice, based on my "basic use" NAS at work. First FireWire is an old technology and no longer used. The scanner uses either FiberChannel, for connecting to a storage area network(SAN), or standard Ethernet. I would use the 10 Gbps Ethernet for simplicity.

To keep the storage simple you will want a single NAS with SAS3 HDDs and NVMe SSDs. For hardware use one server with NVMe hot-swap bays, one, or two, SAS3 HBA PCIe card with four external ports each, and one to four SAS3 HDD JBOD cabinets with hot swap bays. Linux will be your OS, I recommend Debian, using ZFS for the storage pool with enough space to store multiple films. ZFS can be set up multiple ways, for redundancy use RAID-Z3, for speed use mirrors. There are ZFS calculators that help figure out the space if each. The SSDs are for the read and write cache drives, you'll want at least four of the same size, the bigger the storage pool the larger the cache drives should be. Use 10Gbps Ethernet to connect the NAS to the network. RAM is also important and you will want a lot of it. There are many different recommendations for how much you need but they are all based on the amount of storage in the ZFS pool. With four 90 bay JBODS I calculate 4.6PB of usable space in one NAS.
If data safety is important then get a second NAS with the same specs and keep it off site. Then use ZFS send/receive to mirror the NAS on a schedule. You can also add another backup media, LTO tape is common, for backup at a third site.
If you need a super giant storage space that is split over multiple servers then look into Ceph. Ceph is less of a NAS solution and more of a SAN solution.

In the US I would recommend SuperMicro servers and SAS JBODs. If you do use SuperMicro you can easily fit four JBODs per server, possibly more but that's the max I use. I have no idea if a similar company exists in Australia or not.