The above moves by black piece was done so that black bishop in f8 has clear access to a3 in later move that shows an example of thinking a few moves ahead.
The above seemingly careless move by black entices white to take the un-protected pawn in d5 by its bishop in c4.
Now look at the next move by black.
3. ......Ba3 and check mate!
In the above, white King does not have any move because it cannot move in c2, b1 or b2 as these were all covered by black bishops, and nor there any other white pieces that can protect the king. I find these few steps shows an excellent example of planning a few move ahead in chess.
The above technique was first applied by Samuel Standidge Boden in 1853 in a game against Schulder, though there was a variation of it played in Horwitzh-Popert game in 1844. Wiki has nice examples of variations in Boden's mate. Link: http://en.wikipedia.org/wiki/Boden%27s_Mate
More Reference: Build Up Your Chess, The Fundamentals by Artur Yusupov (2007), Page 12.