Wow, I vote this to be best daytime UFO captured on video. I cant imagine its fake or anything from this known World. And no, a B-2 isnt a triangle, is has long fuselage. The Stealth Fighter is more triangular but it doesn't have a giant circle on the bottom. Plus those are old technology, if its Earth made its never been made public.
Because there is no visible point of reference here, it is impossible to say how big or how far away this object is. It could be just a kite on 500' of string.<br /><br />And yes, a B-2 is triangular and they are still being used by the US military. See it here:<br /><br />http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit