When I click "Select all snapshots" checkbox on "Storage / Snapshots" page I see "1 - 6 of 13249 | 13249 selected" on the bottom and I think that 6 snapshots were selected.
Then I click "Delete" and it offers me to delete much more snapshots. I can't even understand how much exactly (and which ones).
This should probably work like in GMail: "All 50 conversations on this page are selected. Select all 5,301 conversations in Inbox"