Looks like the lost an engine.
http://shock.military.com/Shock/vide...Content=169718
-S
PS. Here is the official take on it:
The most expensive crash in Air Force history - the $1.4 billion loss of a B-2 Spirit bomber Feb. 23 - was caused by water clogging aircraft sensors, according to an Air Combat Command report. The two pilots couldn't regain control of the bomber and as the left wing struck the runway, the pilots safely ejected.