I'm not sure. but is this legal:
make a new account, sell stuffs you want to store to that account (same location or zone) for $0 then do the same thing as in the video. you can only put 30 items on sale of the same time both on market and personal trade, right? by doing what i said earlier, you can store up to 60 items, and up to 90 if you have 3 accounts (not to mention the in-game storage space).
Posted this so that other guys know the thing