What are these bugs?????

So, in all my 45 years of vacationing here (including a couple now as tax payers), I don't remember these - have I just never looked down and noticed???

These were all over the coast line today - I've seen the fine black line at the shore line, and always just thought it was old seaweed or driftwood pieces or......something. But noticed yesterday I was covered in bug bites after sitting on the beach all day. This morning, I found billions (literall) of these black bugs (with wings) crawling at the shoreline - what are they?????

http://www.youtube.com/watch?v=ZHt6EQvl15s&feature=youtu.be

Thanks!!