This is a cool concept and all for very large portable storage... But for media I think self-hosted streaming would be much more effective, or locally playing it on a desktop for whatever future media that can't be streamed well. Can't see a use for portable storage this big yet... But as soon as it fits in a smartphone-sized personal device we've got something that can support future media types with unfathomably large data requirements (portable "full-dive" vr like the matrix, AR, retina-resolution visuals etc).
I would personally be thrilled to use this for backups. I only have ~20tb of data on my NAS currently. A couple of these discs every month or two would work out well for me.