AWS Glacier Deep Freeze is designed for this. Something you access a couple of times per year if that, and it's $.99/TB/mo. Price that out compared to a $10k NAS or tape backup that will still need consumables like drives and tapes, and it might be your best option. There are costs on retrieval, but since as you've said this is archive footage that customers might request you could pass that cost down to them.
AWS Glacier Deep Freeze is designed for this. Something you access a couple of times per year if that, and it's $.99/TB/mo. Price that out compared to a $10k NAS or tape backup that will still need consumables like drives and tapes, and it might be your best option. There are costs on retrieval, but since as you've said this is archive footage that customers might request you could pass that cost down to them.