Today people seem to be having a real issue with the hidden chests (revealed with Light of Deldrimor). I've had one chest refuse to open with the message "You have already opened this chest today." (hint: I've not opened it today), and apparently others are getting the same issue. Three other chests DID open for me, but gave no loot. I'm unsure if those chests are acting the same for everyone, but apparently it's a problem other people are also encountering.
Lip synching is just mime karaoke.