Weird Sound on startup - Acura Tl 2007
 

So I just bought an 07 tl with 91,000km and I just realized a clunk/knock sound when starting up. The car starts up okay its just the sound I am wondering about. It seems as though the first start up there is no sound then starting it up after that it gets a bit louder each time.

Here is a video, the sound is a bit loud so please turn your headphones/speakers down and adjust accordingly.

http://https://www.youtube.com/watch?v=2fkxkRla1iU

All input is appreciated. Thanks.