It's your friendly neighborhood librarian here, just sharing two more hints to the identity of our Mystery Guest.
First, you may have noticed (or maybe not) the use of clocks and mention of time in several of our videos and blog posts. These have not been random comments or images.
Second, the old fashioned clothes and the talking proper (that Kyra mentioned here) indicates that the character may be ... well, classic. So you might want to check out this list. (And just so you are not confused the titles in red are ones that Wikipedia highlighted not me.)