alece bro!
I dont think the background music was copied from the video link that you provided. In fact the video you have provided has used the similar track. It seems like any one can use that music if you buy it from the provider. Check out the source link under the youtube video. I dont consider this stealing. They have clearly cited the source. And they arent even making money out of this song. There is a free download link to the song. But i cant deny the fact that its always better to create your own track.

Since you said that even 5 yr old can write a rap song, would you mind writing a nice little rap for me? It would be even better if you would sing it too and post it on youtube. It should't be that hard since you said its for the retards....right?? I assume you'r not a retard. I have a feeling that you could do better than this :)

About the rap VS metal/rock, it all depends upon the preception. If you make your "Hajur Aama" listen to either rap or metal/rock whatever, it would sound her nothing more than a crazy man shouting. I just want to say that you need to respect the people's hard work. There is certainly hard work involved in rap/hip hop. Its not just a genre, its a life stye. You need to live with it in order to appreciate it.

Peace out.

P.S: I am not a hip hop fan but wouldn't mind listening to one if it worth listening :)