Whatbird.com

What kind of bird is this:  http://www.youtube.com/watch?v=E0dZH-iKz48 ?  I found it on the beach in Pensacola Beach, Fl, and have seen them a few times.  They kind of flop up on the shore and just lay there like they are injured, but they aren't actually sick or injured at all.  Their legs are really far back too.

Hi there.  I have a kind of bird near my house (out in the country, near ponds and swamps, next to a forest, about 20 miles inland from the beach) that I hear but never can see.  I think they might be mating right now (Oct.), as they seem to be calling to each other quite often throughout the day.  I can't tell if they are ...