The official Starz Da Vinci's Demons website has 2 new video clips. First is one titled Mystery and the other a preview trailer for next week's episode "The Devil". Both only viewable in US, though the trailer below is viewable to all.
The site also has a few new stills for episode 6 and a synopsis.
'The Devil' A clue from the Turk about the Book of Leaves sends Leonardo to Wallachia, where he encounters Vlad Dracula. Lorenzo and Piero meet the Duke of Urbino. The search for the true spy continues.