Yours, not ours
My shelf
Films you own, want, or have watched. Kept in this browser and nowhere else.
There is no account and nothing to sign up for. Marking a film writes it to this browser's own storage. It is never sent to this site, and no copy exists anywhere for us or anybody else to read. The trade is that a shelf built on one device will not appear on another, which is what the export is for.
This is what a catalogue is for. A 3D disc that is out of print and sitting in a shop is worth buying once, and the reason to keep a list is so you do not buy it twice.