I think it's just its tongue. Vampire bats don't really "suck" blood, Dracula-style; they make little cuts and then lap up the blood.
I've been waiting on some "real" news organization to report on this. I've seen ProMed reports for weeks, but all I could find in a regular news site was a similar phenomenon from last year. 'bout time they got to it.
Well, that may be the coolest thing I've ever seen. I can't believe they can run 2.5 miles an hour! The footage confirms that the pink thing is just a lapping tongue, too.