I would guess he means that the data is encrypted before ever being sent to backblaze. The answer is yes according to http://www.backblaze.com/backup-encryption.html
Rather, it's an optional yes.
Rather, it's an optional yes.
EDIT: Actually, it looks like they can decrypt your data to restore it on their end, so it's a no.
Of course, if you have so sensitive stuff that you cannot accept it ever being on another server in clear text then it still a no on that question.