If you didn't understand the last post and what I meant by the video, allow me to explain.  Hip Hop is about making "a negative to a positive".  It is about portraying your experiences and your surroundings as vividly as possible.  Many people's surroundings and experiences involved in Hip Hop aren't always positive so the music reflects that.  It's a candid look at the forgotten in society and it came from the underground. 

In the immortal words of Biggie Smalls "I went from negative to positive and it's aaaaaall good".  Before I leave let me leave you with another video.  This one is a oldie but a goodie and further explains my point.