Are the chests and urns around the Dragon Priest Altar safe for storage? [The empty ones you see behind you after putting on the Wooden Mask.]

AFAIK, the only "safe" storage is in a house you own, or in the Arch-mage's quarters in Winterhold.

Pity. I wonder why they're all empty.

Well, they're all empty because you looted them. Some dungeon containers respawn. Right now, there's not a really good list of which respawn. Until there IS a good list, you'd be best advised to buy a house, or complete the College questline to become arch-mage.

I've never been to the Altar before. You mean the other Dragon Loot chests? I'm talking about the alternate realm you go into to get Konahrik, all the storage there is already empty.

Ah. Well, you weren't really specific... Again, I don't know. I have every house in the game, I'd never leave stuff I really wanted in chests someplace like that.

I thought the whole "After putting on the Wooden Mask" part specified that quite well...

Anyway, I just thought it would be a lot more convenient because you can just put on the Wooden Mask wherever you need more storage and teleport to some alternate storage realm.

Nope. You must be in front of the altar for the mask to work. So no magic teleport