Wicked man. That's cool.

this is so cool,
could you tell a little bit about this video?

What's the black gunk — it reacts so wonderfully with the speaker's varying sound frequencies!

Sometimes, those black gooey bits almost seem to move like they have intent — (reminds me a little of the Spiderman villain, Venom, doesn't it?) Awesome vid, Joe.

(One critique: I might have wished for cooler/ more contextual word formations rather than "dog" and "cat...something more fitting to the visceral gunkiness?)

It's a non-newtonian fluid. Cornstarch and water in this case (it's also in the video description). Don't know how he/she got it so black, though. :)

Right, to be clear, this video is from user named "urk" via Vimeo. http://vimeo.com/urk