How is collecting a video 80 bytes at a time from a >50 GB and constantly growing database "easily accessible"? If you e.g. compare it to an USB stick or a -account?
OP_RETURN is prunable data, so you can not even rely on "unalterable" or "permanent". If you want to avoid this - you can - you will cause other issues and might solve these two, but you will not have easily accessible data.

Note: Im biased, I dont think I should store your video for you. There are probably alt coins made for this exact purpose. At least I heard about "proof of space" concepts a while back.