What is this helicopter (and probe) in the film "Act of Valor"?
By U.S. Navy photo by Mass Communication Specialist 3rd Class Robyn Gerstenslager [Public domain], via Wikimedia Commons

Yes, it looks to be a Boeing CH-47 Chinook. Above is a photo from Wikipedia showing an Army Chinook with a Navy SWCC boat attached to the external cargo hook, looking almost exactly like in the movie.

And yes, the probe is the refueling probe. It needs to stick out from under the rotors, to prevent the rotors from accidentally cutting the fuel hose. (Although it doesn't prevent this from happening.)