Difficult very difficult to understand it

http://www.youtube.com/watch?v=mLH0c4UhUrk

http://www.youtube.com/watch?v=OHy5g3oe7Ms

http://www.youtube.com/watch?v=zm0YVc0AYq0

http://www.youtube.com/watch?v=7ATstDiosAw

http://www.youtube.com/watch?v=jsQJdmhjJoQ



http://www.youtube.com/watch?v=Bq2veVwM6oI

http://www.youtube.com/watch?v=-kqSPmbymg4

http://www.youtube.com/watch?v=5ZSliX8L-eU

http://www.youtube.com/watch?v=XyexDlccd24