Rated 4 out of 5 stars
Nice. New features a bit buggy. Sometimes hover play doesn't work.This review is for a previous version of the add-on (1.1.1-signed).
If you give me a link to a page on which it fails I can take a look. (email: firstname.lastname@example.org) I know it doesn't work on background images, unfortunately that's unfixable. :(
(Edit: Tumblr should hopefully work better in the latest version.)