Engine sound HELP!!

Hello guys,

I hope everyone is doing fine. Since few month I own a BMW X6 3.5i 2008
Very nice car and drives like an angel. but since few weeks I noticed a strange sound from the engine.
When I open the hood, the engine sounds like a diesel engine. Takatakatak..

Now my question is whether it's normal that this sound is coming out of the engine or not?

I made a video of the engine. Here you can hear clearly the (diesel) sound.

http://Youtu.be/nF2rURDBlp8

I hope someone here can tell me something about this issue.
I also apologize for my poor English typing.