I bought a 2007 Acura TL from carmax with 90k miles , after bringing the car home for couple of days ,I started to noticed a noise when I start the car but only intermittently like 3 to 4 times over a week and half or so, and its when the car is cold
http://youtu.be/Qna6BMS9TFk

 

Hard to tell what it can be. I would take the car back to carmax so they can hear that sound and try to resolve the issue.

 

Pull those plastic covers and check your pulleys/serpentine belt... It sounds like the noise is coming from the transmission area though... You can rule out pulleys and anything tied to the belt by removing the serpentine belt and briefly turning on the car to see if the noise is gone...

 

Give it a try.

 

Thanks guys for the suggestions, the only problem is the noise is only intermittent , so I brought it back to carmax on Monday, we could not get it to act up, I've showed the tech guy there the video, but they are saying they have to get the car to act up there , so on Tuesday the girl that works in the front there said she went to start it up and she heard it but by the time she got the tech it went away, and it's Thursday now and they said the car has not acted up since, I know they have a 30 day warranty on their cars but I'm wondering if they just giving me the run around, if I showed this video to a Acura dealer do you guys think they can figure it out?

 

check your tensioners